Studying can be tough task, specially when you're in college or university.
There isn't time for anything! Almost every free moment you have needs to be sacrificed for your studying.
Subjects like Maths and Algebra, physics, Algorithms , require training, loads and loads of it.
Grab the paper with exercises you did in class and repeat all of them! Do this 2 times, 3 times, 4 times, the times needed until it gets inside your head.
Subjects like psychology, and history don't require as much training, specially if you have good memory. Just read, re-read, and read it again.
Another tip:
Don't study at home. You'll always get distracted by something.
Yeah I know... Its nice to stay at home but there you have food, you have your computer, your harm place! After that, you look at the clock and say:
"omfgfg productive day lost!".
Myself, I can't study for more than 10 minutes and home

. The computer just keeps calling for me.