The DO's:

DO tell us your operating system (like Windows XP Home, Windows 98, etc.)
DO tell us if you installed something recently.
DO explain the problem in as much detail as possible. If you get an error message, give us the full text of it.
DO tell us if this problem only happens on certain occasions or while using certain programs (like it happens in Internet Explorer when I go to mysite.com). Don't forget version numbers, if you can find them, as those are really helpful.
DO be as polite as possible. Believe it or not, we're actually people here trying to solve this problem of our own accord; be rude to us and we just might be rude back by not helping you.

The DON'T's:

DON'T be vague. "My computer keeps crashing" isn't good enough. We need plenty of details: as many as you can manage.
DON'T PM any admins or mods about your problem. We'll get to you and try to fix it, even if that means lamely telling you to talk to your vendor's tech support.
DON'T post screenshots of error messages, windows, etc. unless a staff member asks. That just clogs things up. Type up error messages, etc.
DON'T assume we're all experts! Everyone here has varying levels of experience with computers, and we're trying the best we can. If our solution doesn't work or, heaven forbid, makes things worse, that's no reason to go on a 100 line tirade about how we're blithering idiots and we know nothing about computers! Have realistic goals! Most of us don't even have a computer-related job.

REMEMBER, following these guidelines ensures a quicker, politer, and overall more helpful response. We'd all appreciate it if you followed these guidelines when posting a tech support problem.

Thank you!
--Borg and the rest of the Allforums staff.