When tutoring ESL students, you should always keep in mind not to take anything for granted. Most importantly though, just because someone speaks with an accent, does not necessarily mean they don’t have a firm grasp on the English language and assuming so could be quite insulting. What you might consider common practice or common knowledge could be completely new or unnatural to non native speakers. When working with native English speakers, you can assume that the writer knows what a thesis statement is, that they know what a paragraph basically looks like, and the connotation of cultural idioms. However, with non native speakers none of this can be assumed. To no fault of their own, the non native speakers might not have this information. Writing structures are not universal and can be quite puzzling for some students. Different cultures think in different ways and therefore they express themselves in different ways.
In order for these students to write successfully in America, they need to be tutored on higher level concerns rather and lower level concerns. These students need to understand not only the vocabulary and grammar style in America, but the conventions and nuances of American rhetoric. Asking the student where they would want to start or what aspect of their writing they feel most uncomfortable with can help you prioritize your session. You only have a certain time limit and only focusing on grammar or only focusing on theme might not necessarily be the most productive.
I would recommend not trying to correct every mistake they make. They may feel self-conscious about writing, and even speaking, in another language and dominating the session or “fixing” their every mistake may discourage them from continuing their writing. One helpful tip might be to point out certain sections of the paper and focus on those. Having the student take notes to resort back to while revising this paper and/or working on future assignments could be quite helpful as well. As with any tutoring session, building rapport is important. However, upholding self confidence, bridging cultural differences, and potentially decreasing shame are challenges that can be unique to ESL tutoring sessions.