1) Don't save to your desktop - you can lose access to your equipment w/o warning. (This happened to my wife)

2) Don't bother with HR ahead of time - the good ones will make it seem as if they are on your side - they are not. They work for the company and are there to protect the company's interests - not yours.

3) Talk to an attorney early in the process to know exactly what your rights are and what you'll need to have documented. Can't tell you how valuable that shot of confidence is while everything is going down.