In order to concentrate in studies,first you have to get interest in studying ,you have to choose a Calm place without distractions and then fix your target of studying ,planning is important. Mediatation and exercise also helps to concentrate.Sleep well at least 8hrs a day in order to freshen your mind.Revising of learned things helps you to be perfect in your subjects.
If you are having trouble with procrastination, commit to spending 5 minutes on a particular subject without any distractions.
It's been found that once you are involved with a subject for that amount of time that it is easier to continue "interacting" with it.