Give your son room to fail and learn from the experience
Be there for your son when he needs to talk about whatever
Slow it down as much as possible as it flies by
Get a 2nd opinion on any injury where you think the team trainer is wrong/son is misdiagnosed
Don't stand up in the parent's section after watching the starter shove and say "I love pitchers!!!!" when your son is a pitcher. (not the pitcher who shoved that game and elicited that comment)
Make friends with parents and understand you will get wrangled into convos about their kids, situations, playing time, and other stuff but just listen, don't talk. If you're having a hard time looking them in the eyes....stare at the bridge of their nose.
Don't go out of your way to talk to the HC, PC, or coaches
Enjoy it, lots of kids don't make it to college ball or last long once there.