The errors worth paying for are the ones that pass every automated check: a preposition that is technically correct and unidiomatic, a register that is a shade too formal, a phrase that means something else in one market.
What to put in the public brief
- The language and the market, which are not the same
- Roughly how much text
- What it is for: web copy, an email, an app string
- Whether they are correcting or commenting
Keep the copy private. It is usually unreleased.
What to put in the private instructions
Give the copy and one paragraph you are happy with
The reference paragraph is what stops a proofreader flattening your voice into neutral.
Say what must not change
Brand names, product names, legally reviewed sentences, anything with a claim in it. A well-meant improvement to a claim line creates a compliance problem.
Ask them to mark errors and preferences separately
You need to know which changes are wrong-versus-right and which are how-we-would-say-it. Both are useful; only one is mandatory.
Ask about the market, not the grammar
"Is there anything here that reads as translated or foreign" finds more than any request for a grammar check.
Proof worth requiring
Ask for
The corrected text with changes marked, a short list of preference notes kept separate, and the country they read from.
Do not ask for
A rewrite. If the copy needs rewriting, that is a different task at a different price, and a proofread that arrives as a rewrite is impossible to review against the original.
When this task type is the wrong tool
If the text is not yet in the target language, you need translation or translation review first; proofreading a machine draft without saying so gets you a tidied machine draft.
If the copy is legally significant, this does not substitute for review by someone with liability for the outcome.