There is nothing like the sense of anticipation you feel when opening a care package from home. The care packages can be food baked with love from mom and it can be mailed or shipped by whichever method is cheapest or most expedient. If your mom is a good cook this food can be a good way to make friends with your dormitory neighbors.
It is bad form to come home every weekend with dirty laundry and an empty wallet. Yes there are some parents who will let you do this but part of going away to college is becoming a kind and considerate human being. Just as public flatulence is not acceptable, neither using your mother as a laundromat and your father as an ATM.
On special occasions, and especially on special occasions which you will be unable to attend, it's time to get old-fashioned and sit down and write a snail mail letter. Include an Arbor Day card or whatever memento that can be used to observe and celebrate the occasion.
If your whole reason for going away to college was so that you could discover up close and in person what the phrase "party till you puke" means, I would advise that you not keep parents in that particular loop either.
Well, let's suppose you are not a slacker and that you plan to knuckle down and study and to have a part-time job on the side to cover pizza and the occasional beer. Well as in all things college, the best time to do something is on the weekend. Let's assume that Friday night and all of Saturday are reserved for mind numbing drinking binges and non-stop partying. Then the best time to contact your parents is when you are nursing a hangover on Sunday. You will sound contrite and not at all boisterous as loud noises hurt your head. If you don't trust yourself to speak then e-mail your parents every Sunday morning. Tell them about the classes you are taking and how you are doing. Tell them about the new friends your making and how your roommate stinks and is a pig.
For extra special occasions you can go really old school as in Samuel Morse and send a telegram. Think how excited your parents would be to read a dispatch that announces that you are finally coming out of the closet about your love of goats and dressing up in women's clothing.