The best thing you can do is refine and improve study habits, develop time management skills, and improve efficiency so that school work is manageable once you've entered college, which is traditionally filled with more social opportunities. To ensure that you perform your best in classes, but also enjoy your free time and social time while you're there, refining your academic skills will reduce your stress.
Prepare yourself to leave your comfort zone in college, and to take on new opportunities and make unique friendships. Some of the best people you'll ever meet might be in your class or around campus, and if you're able to get out of your comfort zone you'll be in a great position to meet them! Discover your interests, such that you can explore them further and meet like minded people. At the end of the day, college has endless opportunities so be sure to take advantage of the independence but also be mindful that your performance in college will have an impact on opportunities (jobs, friends, etc.) that will be afforded to you once you leave.