Some Points Of Idiom
From Handling Of Words part of The Complete Plain Words by Sir Gowers(1954)

Agree
Following the example set by approve, agree is showing a disposition to shake off its attendant prepositions to, on and with, and to pose as a transitive verb. "I agree your figures", "We must agree the arrangements for this", "I agree your draft". Some correspondents would have me castigate this, but I do not think there is any great harm in it. It is true that established idiom requires "I agree with your figures", "We must agree on the arrangements" and "I agree with" or (if from a superior) "I agree to your draft". But the change has probably come to stay, and will be absorbed into English idiom.

Avail
The proper construction is to avail oneself of something. Avoid the ugly passive construction such as "this opportunity should be availed of". "Taken" or "seized" or "made use of" will do instead.

Averse and Adverse
It is usual to say averse from, though there is good authority for averse to. (What cat's averse to fish?) But adverse is always to.

Circumstances
It used to be widely held by purists that to say "under the circumstances" must be wrong because what is around us cannot be over use. "In the circumstances" was the only correct expression. This argument is characterised by Fowler as puerile. Its major premise is not true ("a threatening sky is a circumstance no less than a threatening bulldog") and even if it were true it would be irrelevant, because, as cannot be too often repeated, English idiom has a contempt for logic. There is good authority for under the circumstances, and if some of us prefer in the circumstances (as I do), that is a matter of taste, not of rule.

Compare
There is a difference between compare to and compare with; the first is to liken one thing to another; the second is to note the resemblances and differences between two things. Thus:

Shall I compare thee to a summer's day?
If we compare the speaker's notes with the report of his speech in The Times....

Consist
There is a difference between consist of and consist in. Consist of denotes the substance of which the subject is made; consist in defines the subject.

The writing desks consist of planks on trestles.
The work of the branch consists in interviewing the public.

Depend
It is wrong in writing, though common in speech, to omit the on or upon after depends, as in:

It depends whether we have received another consignment by then.

Differ
In the sense of to be different, the idiom is to differ from.
In the sense of to disagree, it is either to differ from or to differ with, which you please.

Different
There is good authority for different to, but different from is today the established usage. Different than is not unknown even in The Times:

The air of the suburb has quite a different smell and feel at eleven o'clock in the morning or three o'clock in the afternoon than it has at the hours when the daily toiler is accustomed to take a few hurried sniffs of it.

But this is condemned by the grammarians, who would say that than in this example should have been from what.

Direct and Directly
Direct, although an adjective, is also no less an adverb than directly. To avoid ambiguity, it is well to confine directly to its meaning of immediately in time, and so avoid the possibility of confusion between "he is going to Edinburgh direct" and "he is going to Edinburgh directly". Here are two examples from recent departmental circulars, the first of the right use of direct and the second of the wrong use of directly:

Committees should notify departments direct of the names and addresses of the banks.
He will arrange directly with the authority concerned for the recruitment and training of technicians.

Doubt
Idiom requires whether or if after a positive statement and that or but that after a negative.

I doubt whether he will come today.
I have no doubt that he will come today.

Either
Either means one or other of two. Its use in the sense of each of two, as in:

On either side the river lie
Long fields of barley and of rye,

or in:

The concert will be broadcast on either side of the nine o'clock news,

is common, and there does not seem to be any good ground for Fowler's dictum that it "is archaic and should be avoided except in verse or special contexts".

Equally
Do not let as intrude between equally and the word it qualifies. Not equally as good, but equally good.

First and Firstly
There used to be a grammarians' rule that you must not write firstly; your enumeration must be: first, secondly, thirdly. It was one of those arbitrary rules whose observance was supposed by a certain class of purist to be a hallmark of correct writing. This rule, unlike many of the sort, had not even logic on its side. Of late years there has been a rebellion against these rules, and I do not think that any contemporary grammarian will mind much whether you say first or firstly.

First Two
For more than a hundred years pretty arguments have been carried on from time to time round the question whether one should say the first two or the two first. Some famous grammarians, notably Dean Alford and Jespersen, have supported the two first, but the majority of expert opinion is overwhelmingly against them. So the first two holds the field. But the point is not important. Everyone knows what you mean, whichever you say.

Follows (As Follows)
Do not write as follow for as follows, however numerous may be the things that follow.

"The construction in as follows is impersonal, and the verb should always be used in the singular" (O.E.D.).

Got
Have got, for possess or have, says Fowler, is good colloquial but not good literary English. Others have been more lenient. Dr. Johnson said:

"He has got a good estate" does not always mean that he has acquired, but barely that he possesses it. So we say "the lady has got black eyes", merely meaning that she has them.

And Dr. Ballard has written : (40)

What is wrong with the word? Its pedigree is beyond reproach. If the reader will consult the Oxford English Dictionary he will find that Shakespeare uses the word. So does Swift; Ruskin uses it frequently, and Augustine Birrell in Obiter Dicta asks
"What has the general public got to do with literature?"
Johnson in his Dictionary gives possession as a legitimate meaning of the verb to get, and quotes George Herbert. Indeed he uses it himself in a letter to Boswell. The only inference we can draw is that it is not a real error but a counterfeit invented by schoolmasters.

When such high authorities differ, what is the plain man to think? If it is true, as I hold it to be, that superfluous words are an evil, we ought to condemn "the lady has got black eyes", but not "the lady has got a black eye". Still, in writing for those whose prose inclines more often to primness than to colloquialisms, and who are not likely to overdo the use of got, I advise them not to be afraid of it. The Americans have the handy practice of saying "I have gotten" for "I have obtained" and reserving "I have got", if they use the word at all, for "I possess." But the usual way for an American to express an Englishman's "I haven't got" is "I don't have".

Hard and Hardly
Hard, not hardly, is the adverb of the adjective hard. Hardly must not be used except in the sense of scarcely. Hardly earned and hard-earned have quite different meanings.

Hardly, like scarcely, is followed by when, not by than, in such a sentence as

"I had hardly begun when I was interrupted".

Than sometimes intrudes from a false analogy with

"I had no sooner begun than I was interrupted".

Help
The expression "more than one can help" is a literal absurdity. It means exactly the opposite of what it says. "I won't be longer than I can help" means "I won't be longer than is unavoidable", that is to say, longer than I can't help. But it is good English idiom.

They will not respect more than they can help treaties exacted from them under duress. (Winston Churchill, The Gathering Storm.)

Writers who find the absurdity of the phrase more than they can stomach can always write "more than they must" instead.

Inculcate
One inculcates ideas into people, not people with ideas; imbue would be the right word for that. A vague association with inoculate may have something to do with the mistaken use of inculcate with.

Inform
Inform cannot be used with a verb in the infinitive, and the writer of this sentence has gone wrong:

I am informing the branch to grant this application. He should have said telling or asking.

Less and Fewer
The following is taken from Good and Bad English by Whitten and Whitaker:

Less appertains to degree, quantity or extent; fewer to number. Thus, less outlay, fewer expenses; less help, fewer helpers; less milk, fewer eggs.
But although few applies to number do not join it to the word itself: a fewer number is incorrect; say a smaller number.
Less takes a singular noun, fewer a plural noun; thus, less opportunity, fewer opportunities.

Order (In Order That)
May or might are the words to follow "in order that". It is incorrect to write "in order that no further delay will occur" or "in order that we can have a talk on the subject". And it is stilted to write in order to where to will serve equally well. Jack and Jill did not go up the hill in order to fetch a pail of water. English idiom recognises so as to and so that they might as alternative ways of expressing purpose, but has not yet admitted the American so without that ("so they could fetch a pail of water").

Otherwise
Twenty-five years ago Fowler pointed out that this word was having "very curious experiences" in that, although an adverb, it was being used more and more both as an adjective and as a noun. These experiences have certainly not abated since then.

The adjective that otherwise dispossesses is other. This is exemplified in such a sentence as

"There are many difficulties, legal and otherwise, about doing what you ask".

The noun that otherwise dispossesses is whatever noun has the contrary meaning to one just mentioned. This is exemplified in such a sentence as

"I will say nothing about the reasonableness or otherwise of what you ask",

where the word replaced is unreasonableness. (Sometimes, Fowler might have added, it is used as a verb too, e.g.

"we shall be glad if you will now confirm or otherwise your desire to avail yourself of our offer",

where the word replaced is deny.)

Fowler condemns both these as ungrammatical. Since it is just as easy in the first case to write other and in the second either to omit or otherwise or to substitute the appropriate noun, there is no reason why one should not be on the safe side and do the grammatical thing. But it would be wrong to leave the subject without quoting Dr. Ballard:

A new pronoun is as rare a phenomenon as a new comet. Yet it dawned on me the other day that a new pronoun had insidiously crept into the English language. It was heard on everybody's lips, it was used on the platform and in the press, it figured prominently in blue-books and official papers. And yet I could find it in no dictionary — not, that is, as a pronoun — nor could I discover it among the lists of pronouns in any grammar, however modern. Still, if the current definition is correct, the word is beyond doubt a pronoun. The word is otherwise. A committee is appointed by an educational body to report on the success or otherwise of the new organisation of schools. What does otherwise stand for? Why failure, of course. And failure is a noun. Therefore otherwise is a pronoun. . . . I thought at first with Mr. H. W. Fowler that otherwise, so used, was not a pronoun but a blunder. But when I considered the people who used it so — schoolmasters and school inspectors, and ambassadors, and statesmen and judges on the bench — I could not accept Mr. Fowler's views. For I would rather wrong the dead — dead languages that is — and wrong myself and you than I would wrong such honourable men. There is no help for it. Otherwise is a pronoun.

Sometimes other gets its revenge, and supplants otherwise.

It is news to me that a sheep improves the land other than by the food fed through it.

Prefer
You may say "He prefers writing to dictating" or "he prefers to write rather than to dictate", but not "he prefers to write than to dictate".

Prevent
You may choose any one of three constructions with prevent: prevent him from coming, prevent him coming and prevent his coming.

Purport (verb)
The ordinary meaning of this verb is "to profess or claim by its tenor", e.g. "this letter purports to be written by you". The use of the verb in the passive is an objectionable and unnecessary innovation.

"Statements which were purported to have been official confirmed the rumours"

should be

"statements which purported to be official confirmed the rumours".

Regard
Unlike consider, count and deem, regard requires an as in such a sentence as "I regard it as an honour".

Require
Require should not be used as an intransitive verb in the sense of need as it is in:

You do not require to do any stamping unless you wish (you need not) and
Special arrangements require to be worked out in the light of local circumstances (special arrangements will have to be. . .)

Substitute
To substitute means to put a person or thing in the place of another; it does not mean to take the place of another. When A is removed and B is put in its place, B is substituted for A and A is replaced by B. Substitute is wrongly used in:

The Minister said he hoped to substitute coarse grain with homegrown barley,

The Minister ought either to have used the verb replace, or, if he insisted on the verb substitute, to have said "to substitute home-grown barley for coarse grain".

Such and So

It will take some time to unravel such a complicated case.

There are those who say that this is unidiomatic, and that we ought to say "so complicated a case". But if we choose to regard them as pedants we shall have Fowler on our side, and so cannot be far wrong.

Unequal
The idiom is unequal to, not for, a task.

Very
One of the most popular objects of the chase among amateur hunters of so-called grammatical mistakes used to be very with a past participle — "very pleased", for instance. It is true that very cannot be used grammatically with a past participle — that one cannot, for instance, say "The effect was very enhanced"; we must say much or greatly. But when the participle is no longer serving as a verb, and has become in effect an adjective, it is legitimate to use very with it as with any other adjective. There can be no objection to "very pleased", which means no more than "very glad", or to "very annoyed", which means no more than "very angry". But it will not do to say "very inconvenienced" or "very removed", and in between are doubtful cases where it will be as well to be on the safe side and refrain from very.

Worth
Worth has a prepositional force, and needs an object. This object may be either while (i.e. the spending of time) or something else. It is therefore correct to say "this job is worth while"; it is also correct to say "this job is worth doing". But one object is enough, and so it is wrong to say "this job is worth while doing".

Worth-while as an adjective ("a worth-while job") has not yet reached more than colloquial status.