What can I do to maintain good grades when starting college?

The biggest factor to my success was accepting I was going to have to sacrifice time doing things I wanted to do to achieve the goal of graduating with good grades. You need to understand you will have to miss a concert, birthday party, time with family, or time with friends if you are serious about doing well in school. You should think about how much you are going to balance things or deal with that disappointment. You should also prepare those close to you so they can support you during those sacrifices instead of making them more difficult by making you feel guilty for missing activities.

College professors can vary in level of strictness. In general, the college environment is going to be way less strict than you'll be used to, simply because you are the one responsible for getting yourself to class, turning in assignments, etc and your teachers won't always be as involved. That being said, if you do go to most/all of your classes, prioritize getting your work done, and don't let yourself fall behind, you will do fine.

Compared to high school, college is a lot less about "just getting the grade" and a lot more about actually trying to learn the material as a good amount of it could apply to your future career. If you take an interest in the material each class has to offer, you'll be more actively involved and will get good grades.

For me, the key to success in maintaining good grades in college was time management. Life in college is much more unstructured than it was in high school. Your time in class may even be less than it is today. But, my professors assumed that I would accomplish more work out of class then my high school teachers ever did! You will also be faced with more choices on how to spend your time - activities, sports, social events. You need to plan your day and week to accomplish what you need to do for school, with what you want to do for enjoyment. And like Alyssa said above, you may have to miss a fun activity to do schoolwork! However, in my opinion, if you are asking this question, you are already positioning yourself for success! Good Luck!