On the mundane things of what you should buy, bring etc. don't forget they have stores wherever your son is heading
. Ours brought way too much with him.
Have your son check in with his roomate if he knows who that will be and coordinate some of the stuff they'll bring. Good way for them to "meet" and start connecting.
Visit the school website yourself and familiarize yourself with as much as you can about school calendars, policies etc. Not so you can instruct or interfere, but so you have a clue as to what's going on (or should be going on).
It's their college experience, so let your son set the ground rules (within reason
for phoning, emailing, visiting etc.
The first few weeks or so will be tough, by Thanksgiving break it will typically have all come together.
Then the spring baseball season... best advice we got is that the best hope for a freshman player is that he'll become a sophomore player. (keep the dreams alive but the expectations in check as a freshman).
Have confidence that you've done your best the past 18 years to raise your child and that they will find their way.