Should you send a paper to peer-review before or after having it proof-read and possibly edited by a native speaker (this is especially relevant if you are not a native speaker of English)?

In favour of sending it to a native speaker or copy-editor only after the peer review speaks the fact that the peer review might require substantial changes and that you possibly don’t want to pay twice.

In favour of sending your article to a copy-editor before the peer-review, however, speaks the fact that reviewers are human beings and, like all human beings, they are likely to have implicit biases they are not aware of. An English form which looks careless might suggest to them that even the content of the article is likely to be not well-researched. This, by the way, applies not only to a careless English form, but also to careless bibliographies, missing titles and the like. All of that is not substantial, but add to that an unusual topic or way of approaching things and you increase your chances to be rejected.

However, how to avoid paying twice for almost the same service?

1. Agree in advance with the native speaker or copy-editor about the following procedure: After the peer-review, highlight changes in red and ask the same native speaker or copy-editor to focus just on them. If it is the same person, they will accept to charge you only a limited additional fee.
2. See if you can get some help from a friend or colleague who is native speaker and, in exchange, help them with something else. I, for one, am more than happy to help my Japanese colleagues with (a first help concerning) their English if they in turn help me understand Japanese articles. The same applies to further languages, I am sure.
3. Last, there is always the possibility to correct all on your own. It takes time, but it is surely doable. I would not recommend this appraoch, though, because it takes much time to see mistakes in your own writings and it is less time consuming to instead help someone else reading their stuff while they read yours.

What do more experienced readers do?