WHERE? First of all, you need to decide where you are going to study. In an optimal situation, a student should have their own room to do school work, since a lonely place helps concentration. However, if this is not your case, you can go to the local library, outdoors or in a cafe as an alternative, preferably early in the morning or really late, when there isn’t a lot of people.

WHEN? Get a study routine and stick to it. If you are like the rest of us mortals, you will try to make up excuses not to open that book, but if you aren’t strict with yourself you will end up procrastinating and leaving things for the last day.
Short periods of studying in different days are more effective than one long session since our brain also gets tired and may reach a point when it won’t absorb more information.

WHAT? There is no limit to the extension or depth of your studying. That’s why you need to plan carefully the general organization of your tasks, the order in which you are going to perform them and the time you will spend in each one of them, according to their difficulty.
HOW? The secret of good academic performance is knowing what works for you. Some study techniques suit people with great visual memory, while others focus on practical learning. Experience a little bit and find out the best options for every subject (you don’t want to study maths the same way you study history).

Personally I think it’s essential to combine interest, comprehension and practice in order to learn. I know you can’t choose whether if you are into the subject or not, but try to make it at least a little bit interesting. As for comprehension it is pointless to just read through your book pages, you need concentration to comprehend what the meaning of what they say is. Then you want to synthesize the main ideas of the text for easy memorisation. Once this is done you can check what you have learned through practice and go back to the previous step if there is something your brain hasn’t retained.