I take 20mg ritalin on a regular basis in college and here is my advice to you:
Ritalin is much less addicting than adderall and still definitely gets the job done for long classes, studying, papers, etc.
Time release pills are a bad idea.
If you are actually finding yourself not paying attention in class and if it takes a while to focus long enough to write a paper then I think ritalin could definitely help you. If you just take it orally then it's effective but the side effects are still minimal. I've never had trouble sleeping and the comedowns aren't noticeable unless I take more than I should. I snort it sometimes just for shits like if my stomach is full (cuz it doesn't work on a full stomach) and it's nothing crazy. It speeds you up a lil but not too much like adderall would. If you don't have trouble in school then I wouldn't mess with it.
sparknotes: if you actually have trouble in school or writing papers, etc then try some ritalin. Adderall is not worth trying unless you know you have serious ADD/ADHD. Don't mess with study drugs if you are studying well already. oh and to you guys who say "just learn how to study and don't be retarded" everyone is different and for some people sitting down and focusing or studying is a daunting task and these drugs can actually help a lot and not fuck you up.