I use Sandboxie with a browser instance without cookies or cache. It automatically deletes files after closure. Only the browser is allowed internet access.

For specific services like my primary email, I have an isolated Firefox instance keep the cookies for that service only. I don't use that instance for anything but that service. Is there anything I'm giving them (besides what information you give by using the service at all of course)in keeping the cookie? Just want to be aware of any risk I may have overlooked.

I just found my new fave FF extension. Thank you for sharing this!