Studying in college means more independent learning than in high school. It is possible to go all As in college even though you are doing average in high school. The key is “independent learning”. You get everything served up to you on a silver platter in high school while in college you need to buy that silver platter then polish it yourself. There is no schedule in high school, you are free to make one your own, it’s up to you to make one and stick to it. Let’s start with a good study habit, you never want to play “catch-up” with the courses you are taking. Discipline yourself to always follow the course, get any question you need answering, that’s what the professors are there for. Then there is the self-study. You want to read up on those stack of thick expensive textbooks, highlight all the things you think are important and have them ready to review. Reviewing is important since it keeps the topic fresh in your mind. If you can’t do any those immediately, then condition yourself by always attending the lecture available to help you adjust. In time, you will get used to the environment and hopefully start working hard.