I run my browser in incognito mode. Each launch a script creates a new profile directory specifically for that launch. When I quit the browser it deletes that profile directory.

For every activity, email, a specific search, an online purchase, an issue report, accessing personal information, etc., I'll launch a separate instance and within that instance I'll restrict my tabs to only that purpose.

I don't save passwords or bookmarks, both of which are stored elsewhere.

I'm not particularly worried about tracking by being fingerprinted, I'm much more concerned about data leakage, either inadvertently or maliciously.

Rebooting is an utter pain in the arse, but I put up with it and use the opportunity to clear my slate.

Edit: I don't create the profile directory manually, it's a little bash script.