Before you start studying, figure out your schedule so that you are able to give your full concentration on your studies.
Mix up your study schedule by using different methods of revision and also, mix up the subjects so as not to get too bored.
Read to understand what you have read. Sometimes, our brain cheats and we don’t realize it. We read something and think we have absorbed it but we have not. The best way to check is to test yourself on the material. Come up with questions that might be asked in an exam, answer them and see if you get them right. If you can, then you have read to understand. If not, you need to start again.
Be specific about your goal. Do not say study biology but instead say complete chapter 8. That is specific and gives you a goal to accomplish within smaller time frame.
Do away with all distractions and concentrate. It is human nature to get distracted and want to do fun things. Figure out how to create a space where the only goal is to study and nothing else.
If there is something bothering you, write it down to deal with later. If you have to deal with it right away, then go do that. Come back when your mind is ready to study and get down to it.
Always have a reward of some sort when you have accomplished your study goal of the day. Incentives are good for you.
Figure out that schedule and stick to it.
Make sure you come to your study session problem free. Emotional distress can affect the way you perform. Deal with your personal issues before you start.
Take responsibility for yourself. That is the biggest and best thing you can do for yourself. It makes your success or your failure your own.