It is also sensible to make your files are as portable as possible. To ensure this; they should contain only visible 7-bit text; and the filenames should contain at most eight characters (plus the three letter extension).
It is also useful if local classes or packages have a common prefix, for example the University of Nowhere classes might begin with |unw|. This helps to avoid every University having its own thesis class, all called |thesis.cls|.
If you rely on some features of the LATEX kernel, or on a package, please specify the release-date you need. For example, the package error commands were introduced in the June 1994 release so, if you use them then you should put:
\NeedsTeXFormat{LaTeX2e}[1994/06/01]