One of the things that I like to do before I say yes, is to check out that an author's work fits in with the stuff that I read (I do have a wide reading range, but there has been occasions where sometimes things haven't worked out). So, a couple of things that I think you should know.
1. Timeframe - I will try to give an estimated timeframe to getting a review out or reading your book, although I may not always be able to fit them in that time (mainly because I work full time)., or if I have some previous reviewing obligations (however, this changes, if I think I can fit them in!)
2. I don't usually post a review if its anything below a three star on Goodreads (however, I don't usually use stars on the site, but obviously I have to on goodreads and Amazon)
3. I post on Goodreads, and Amazon as well as my website, and also on Instagram)
4. If I am not getting along with the book, I will let you know and maybe we could look at another way to get some exposure for your book (something like an interview or a guest post). I am not saying this would happen, but in these cases, I like a bit of a backup plan. It maybe that just because I don't fit with a book, it doesn't mean others won't.
5. Obviously, all opinions are my own, so if there is some part of a book that I don't think fits or I didn't get along with, I may make reference to it. Although my aim is not to be negative, I may say something that you may not agree with.
6. I read on kindle so .mobi is preferred (or any other of the Amazon file types). However, I can work with other file types. I also read physical books as well.
I hope this helps. I try to give clear expectations to authors who have done so much work with their books and whilst I recognise that most of those points cover negative aspects, I try to be up front with people, so it gives a decent working relationship.