Best practices references
The Essential Guide to LaTeX2ε Usage (l2tabu) explains some of the most common mistakes in LaTeX usage.
The AMS's Short Math Guide for LaTeX, besides being a good summary of math support (both native to (La)TeX and in the AMS's packages), includes a lot of good advice about typesetting math with LaTeX.
Though apparently removed from Stack Overflow1, there is a similar question available at archive.org: Best practices in LaTeX [closed]
The answers are quite useful.
- https://stackoverflow.com/questions/193298/best-practices-in-latex