In my 10th grade, when I was in Nayak's Tutorials, they had given us a tip. Since tenth is one of those crucial years of life and education, everything has to be perfectly studied. I was an average student, and in tenth, I got 90.18%, which came to me like a serious shock.

I don't really know how I studied, but I guess the only rule is: whatever you study, study it deeply, or study everything. 

It can be elaborated in these words: If you have enough time to study, see to it that you do it thoroughly, and deeply. And if you have less time with you, then study everything, no matter how roughly you do it.
Don't leave any topic for option, unless you really cannot understand it, and you are almost about to bang your head on a wall. Often in maths, after trying one type of sum, I used to give up, and go on the next topic.
So if this is the case, then you can leave a topic for option. But see to it that you don't skip many topics.




Anyway, talking about the diagrams; it is one of those simple tips for studying, where you have to draw a perfect diagram, and stick it to the wall you're mostly near, for almost the entire day. (For me, it is the wall near my computer table.)




This will be helpful in remembering the diagram, and its details. We won't literally care to see the diagram, but it'll be in your head, always. And at least you will remember some part of it.

Follow this tip a week before the exam, and stick all the important diagrams on the walls.

P.S. The Diagram is of a DLSR camera and explaining how it works. And it is for photography subject. This was my fourth one, and hence it is NOT perfect. I was tired drawing the same thing, again and again.

Anyway, I hope this helped, and comment below if you follow this tip already.