My advice is: take notes(you may not look back at them, but write down everything you think is important!), sit at the front of the class if possible, try to spend as much time studying or working on homework as long as the class is, so say you have a 50 minute class three times a week, you should spend 150 minutes on outside school work. Seems like a lot, but it will work in your favor, I promise!

Good luck! If you need help, I'd gladly try to help ya out!