The book I mentioned is an excellent way to test yourself on the material; it is all most students need once the material has been properly explained.
In science & math classes, many good students find they need to spend 6-10 hours per week outside of class studying, doing homework, and doing practice problems. This is for each such class taken.
There is a recent book that you might want to read over the holidays to understand how to learn effectively, titled “Make it Stick”. Written by 2 of the leading researchers, it covers not just the theory but practical application. A pair of articles about studying for math classes are [On Becoming a Math Whiz: My Advice to a New MIT Student](On Becoming a Math Whiz: My Advice to a New MIT Student - Cal Newport) and [How to Ace Calculus: The Art of Doing Well in Technical Courses](How to Ace Calculus: The Art of Doing Well in Technical Courses - Cal Newport)