Communicate, Communicate, Communicate
After you've had the initial ground-rules conversation with your mom, keep the ball rolling. Don't assume everything's going to be hunky dory if you've had one good talk -- the lines of communication need to remain open. You'll make yourself crazy by reporting every single detail, but if your mom seems to need constant updating, humor her. Her urge to nag might be nipped in the bud if you keep her in the loop.