Well, the rules are actually pretty simple, as long as you don’t try to trick them.

• Don’t sign up for more than one account with the point of being your own friend. That will be considered cheating and you’ll loose you’re prizes and friends.
• Avoid using that same computer you used to sign up,  to sign up your friends. It can be detected by FreebieJeebies and also multiple account. This can lead to account termination. The best scenario is one account per computer/IP.

Don’t risk it to see you prizes blocked. Just follow the instructions and you’ll be fine.