If your account is compromised, the one thing that you must do is change your password. I've already explained how to do just that in this tip. The other thing, though, might be to run some searches for some of the popular keywords that the hackers in this study used when vetting an account.
Here's what the hackers who compromised Google and University of San Diego:
Search for those keywords on your email account. Be sure to delete any emails with that information on it so that if the worst happens and hackers do take over your account, they won't find anything of value.