Well, it may sound obvious, but go to class. You would be surprised how many people forget this basic step.
Get to know the faculty teaching your courses. Ask them questions. Go to study sessions. Go to office hours. Not only will you learn more, but you will hopefully get to know people who will eventually write letters of evaluation for you.
Generally it is easier to connect with the professor and the academic material in a large class by sitting toward the front and in the middle.
Be professional about your classes –– be on time, turn in your work by the deadline, don't make excuses, be polite, get help when you need it, and turn off your cell phone in class.
Think about what is being said in class –– don't just write down every word in your notes.
Re-read your class notes from the beginning of the course to the current point frequently –– every day if possible.
Use a planner to manage your time.
Keep up on class reading. The material has been assigned for a reason –– you will learn more if you are reading the pertinent material as it is being discussed.
Don't allow yourself to become bogged down. If you aren't understanding things, go get help. Few, if any, of your professors are psychic. They don't necessarily know when you are having problems or not understanding things unless you ask for help.
It may be better to withdraw from a class rather than earning a failing grade. You need to monitor your grades and the withdrawal dates. There may be other considerations, however, that you need to discuss with your academic advisor such as the implications for financial aid, NCAA eligibility, coverage on your parents' insurance, visa status, etc.
Learn the rules for academic honesty and do not break them. There is no faster way to be tossed out of college than breaking plagiarism and other academic honesty rules.
Take care of yourself. Studies show that getting sleep before an exam is a good thing. Keep up with your studies so you don't need to cram. Find ways to relax. Eat a healthy diet. Wash your hands a lot and avoid touching your eyes and nose to prevent colds and flus that hit during midterms and finals.