At least in the begininning, don't stand out. Don't be first, don't be last. Don't mention your dad's service, as they might use that for some psyops against you. Don't brag about anything you're good at, be it running, shooting, or whatever. Be middle of the pack.
Give 100% during drills, exercises, PT, and everything else. You get out what you put in.
Don't worry about tomorrow, worry about today and the task at hand. Your instructors have everything planned out and ready for you, all you have to do is do what you're told.
Mouth shut, eyes and ears open. If they teach you something that you've learned differently, do it their way anyway. Keep an open mind as you go along.
When you get near the end, and the instructors open up a bit, don't hesitate to talk with them. You may develop a good friendship with some of them down the road, and the networking may be of assistance to you later on.
Above all else, Good Luck!