My work is almost exclusively with ESL writers these days, most in Japan and China but from pretty much all continents except Antarctica. To cooperate effectively with them, I've worked hard to learn about their culture and language, and always keep that in mind as I work. In addition, I work hard to revise and simplify my explanations, questions, and comments so that they will be easier to understand, explain more about what I've done, and go the extra mile to avoid embarrassing anyone; "face" is far more important in Japan and China than it is in the West, so avoiding direct criticism is very important indeed. I once spent half an hour trying to come up with wording that would tell the author he'd missed something that any reasonably educated undergraduate should have known without communicating the message "you're an idiot". I succeeded well enough in sparing him this embarrassment before his colleagues that he subsequently included my suggestions on this topic in his future research.