Idiom is language peculiar to a people or to a district, community, or class. It's also an expression in the usage of a language that is peculiar to itself either grammatically (as no, it wasn't me) or in having a meaning that cannot be derived from the conjoined meanings of its elements (as Monday week for "the Monday a week after next Monday").
Do not use an idiomatic expression unless you are certain you have it correct. Otherwise you will alienate your readers, and it will cost you if you are aiming to persuade.
Among the most persistent word-choice issues are those concerning prepositions. Which prepositions go with which words? You imbue A with B but instill B into A; you force A into B but enforce B on A; finally, A implies B, so you infer B from A. And that's only the beginning of it.
Listed here are some of the words that most often give writers trouble. Where more than one preposition is given, the bracketed terms show the context where each is appropriate. Where two prepositions are followed by a single bracketed term, either can be used in a similar context. The notation "none (transitive)" indicates that no preposition is used when a verb is transitive. Examples of the first item in the list might be abide with me; to abide by an agreement; I can't abide him.
- abide (vb.): with [stay]; by [obey]; none (transitive)
- absolve (vb.): from [guilt]; of [obligation]
- account (vb.): to [a person]; for [a thing or a person]
- admit (vb.) ("acknowledge"): none (not to) (transitive)
- admit (vb.) ("let in"): to, into
- admit (vb.) ("allow"): of
- bank (vb.): on [rely]; off [carom]; at, with [a financial institution]
- blasphemy (n.): against [a religious tenet]
- coerce (vb.): into [doing something]
- cohesion (n.): between, among [things; groups]
- compare (vb.): with (literal comparison); to (poetic or metaphorical comparison)
- comply (vb.): with (not to) [a rule; an order]
- consist (vb.): of [components (said of concrete things)]; in [qualities (said of abstract things)]
- contemporary (adj.): with [another event]
- contemporary (n.): of [another person]
- contingent (adj.): on (preferably not upon)
- depend (vb.): on (preferably not upon)
- differ (vb.): from [a thing or quality]; with [a person]; about, over, on [an issue]
- equivalent (adj.): to, in (preferably not with)
- hegemony (n.): over [rivals]; in [a region, a field]
- instill (vb.): in, into (not with) [a person]
- oblivious (adj.): of (preferred); to [a danger; an opportunity]
- reticent (adj.): about [speaking; a topic]; in [manner]
- vexed (adj.): with [someone]; about, at [something]
If any of these are new to you, great! Now you're informed, so why not try using one or two in your next memo, proposal, or business letter? Even your next e-mail!
Source: The Chicago Manual of Style