This book is about writing in the professional mathematical environment. While the book is nominally about writing, it's also about how to function in the mathematical profession.
While technically intended for high school students, this is an excellent, approachable guide for anyone writing a math research paper for the first time.
Some of the information here related to electronic resources is outdated, but the book remains an excellent and humorous guide for details of grammar and usage, advice for new English speakers, and specific guidance for writing and presenting theses, conference talks, and posters.