Summer is the time where you're able to retake a class you may not have done well in or to start taking new classes you couldn't find the time to take during the regular school year. The problem with summer classes is that they are usually accelerated, meaning more content is covered in a shorter period of time.
1. Manage your Time!
-- Focus on your classes. The most important thing during summer classes is keeping up, getting things done ahead of time and preparing. However, allow yourself time to do other things besides just school and work (if you are employed). You're allowed to have time to yourself and enjoy your summer. If you don't focus on other things besides school you will go stir crazy.
2. Have a good sleeping schedule!
-- Leave the late and wild nights for Friday and Saturday. Summer is known for sleeping in and not having to worry about responsibilities. But when you have a 9 a.m. class scheduled, because it was the only time the class was offered, you're going to appreciate the fact that you went to bed at a decent time.
3. Find places to study on or off campus that aren't always inside!
-- Studying inside all summer can get depressing, so venture off! Take your books to the beach with you, get yourself a blanket and find a nice grassy area to sit on campus, or go to your favorite coffee shop and sit outside!
4. Stay Active!
-- This is something I've just learned helps! Go the gym, do some at home workouts, keep yourself busy and awake. Most importantly, stay fit and eat healthy. It will make you feel better physically and mentally!
5. Don't miss class!
-- Missing class in the summer should only happen if you truly can't make it due to a solid reason. Missing one day of class during the summer semester can put you behind greatly, because the amount of material being covered in one day is much greater than in any other semester.
Taking summer classes can be stressful, especially because you aren't able to have a normal summer like everyone else. However, the way I see it, it keeps your mind fresh. When you're in classes all year instead of just the fall and winter semesters, it's easier to transition from semester to semester. You don't have to push yourself to get back into the study groove and the sleep schedules. It can also help your fall and winter schedules to be the way you want them if you can get those extra classes or retakes out of the way in the summer. It gives you a chance to get a leg up and get ahead and ready for higher level classes, as well as giving you that chance for a redo if needed.