When it comes to study stuff, different subjects will require different approaches.
First you must mention what subjects you are talking about.
Since I am in the science stream, I can help you with Physics, Chemistry and Biology only.
Here are some links for chemistry, check them out.
Have a look at these, at least you will have a idea, how to start.
If you don’t have science subjects, mention those.
So that other users can help you.