Am I studying properly?

Is it wrong that I spend a few hours studying for one class and not really put time into another class? For me personally this happens with textbook based classes. I have trouble studying for textbook classes for some reason. How should I handle these?

Here are some tips:
http://talk.collegeconfidential.com/college-life/1920853-college-is-a-step-up-from-hs-16-tips-on-doing-well-in-college.html