1) Don't post personal information online (eg. Name, credit card, address, current location?, date of birth, sin number/social security number, etc)
A lot of people use foursquare and twitter to tell people where they currently are. Are you aware that Google Searches twitter and the results from your twitter posts can come back in search results (depending on privacy settings). That means someone could search google and find out where you are or where you are going. Scary stuff.
2) When you are doing searches make sure you sign out of Google first. As an added safety measure delete your cookie before and after you click a link result that way they are will not be able to track cross site links.
Alternatively you could create a dummy google account used just for search.
If you have other suggestions please feel free to comment here.