Live life fully while you're here. Experience everything. Take care of yourself and your friends. Have fun, be crazy, be weird. Go out and screw up! You're going to anyway, so you might as well enjoy the process. Take the opportunity to learn from your mistakes: find the cause of your problem and eliminate it. Don't try to be perfect; just be an excellent example of being human.
Some of the biggest challenges in relationships come from the fact that most people enter a relationship in order to get something: they're trying to find someone who's going to make them feel good. In reality, the only way a relationship will last is if you see your relationship as a place that you go to give, and not a place that you go to take.