To echo what others have said: keep your mouth shut and do what they tell you. Everyone in your platoon will at some time or another fall under the scrutiny and ire of a drill sergeant, so keep a low profile and don't draw attention to yourself in a negative way. If you don't understand something, don't be afraid to ask to have it repeated, they might yell at you for asking, but actually prefer to explain again rather than have you screw up.
The other thing: work on upper body and cardiovascular fitness NOW. Be in very good physical condition when you get there. If you smoke, quit now because there is a no tobacco ban in basic. Get plenty of rest and sleep now, because you will be in a stressful environment. Get with a vet or a current service member and learn how to make a bed before you go (hospital corners). Mastering a few things like this now will save you time when you get there because you will be ahead of the learning curve. Learn the rank insignia now, and who to salute and who not to salute, it wouldn't hurt if you learned some of the facing movements: about face, right face, left face, parade rest and attention. The more you learn now, the less you have to learn in basic training.
Learn to work together and put aside any personal predjudices. The squad you are assigned to will have to work as a team.