(We hate the word "rules.")
1. If you have a blog, post to it fairly regularly. (Oops!)
2. If the client has to call you for an update, you've dropped the ball.
3. If your call to a reporter is going to begin "Just wanted to make sure you received my email," don't bother unless you have an added tidbit of info or angle to suggest that wasn't in the email.
4. If you're not sure you have the right email address, call the reporter before you send the email to confirm, not afterward.
5. If you're contacting the same reporter about two different clients, send two different emails.