"Avatar doesn't update" troubleshooting

Instead of waiting for people to report that their avatars don’t update and then tell them to clear their cache and so on, how about a sticky post with step by step instructions for the most common fixes? Something like:

1. refresh the page
2. clear your cache
3. delete your cookies
4. use a different browser
5. reinstall your operating system
6. burn a graphics card at full moon to summon the tech demon and ask him to fix your stuff