Microsoft Word
Dr. Maite Taboada has written a guide on her website detailing how to use Microsoft Word, specifically for linguists. If you're struggling with tables or numbering examples, this resource will help you.
LaTeX
This is an open-source textbook that covers all the basics of using of LaTeX for linguistics.
This page has demos of tables, example numbering, syntactic trees, the IPA, and phonological rules.