If you are unsure about certain typographical issue when writing maths, such as spacing, breaks, hyphens, etc. then you can consult the book Mathematics into Type by E. Swanson. (It is freely accessible.)
There are also some books and articles that are more rigid on how you should write your mathematics. However, I think although some of these rules can improve the quality of piece of writing dramatically, especially for the reader, we must not forget that mathematics is a highly social activity and at the end of day any mathematics paper reflects the idiosyncratic habits of thinking of its author, and these could make an otherwise monotone stylish. Speaking of stylish papers that come to my mind are: I agree with Alain Connes that
My main point is that mathematicians are so “singular”, (and behave like fermions as opposed to the physicists who behave like bosons) that making general statements about them often produces something obviously wrong or devoid of any content.
Finally, I cannot finish this point without mentioning that during my chasing of various interesting links folks shared here and there, I came across a book by Carl E Linderholm from 1972. Among other things,
Mathematics made difficult is a humorous and entertaining satire of stereotypes of French mathematicians, the project of formulating all of mathematics on category-theoretic foundations, and some other pedestrian jokes. Here is a quote that stuck in my mind from it:
The simpler the things a man gets difficulty out of, the better his mathmanship.