There is a difference in knowing how to do things and actually being able to do things. By just knowing how to do things does not make you expert.

Pure mathematics is, in its way, the poetry of logical ideas. ~Albert Einstein

Learning mathematics is like learning the art of solving problems (actually doing) and just knowing formulae and concepts (acquiring knowledge).So if you want to improve your mathematics, you need to focus more and more on problem solving instead of just reading theories, formulae, and solutions. In mathematics students must move from rigid reliance on rules without understanding (rule orientation) to an understanding of mathematical concepts and flexibility in problem solving (Concept orientation).

If people do not believe that mathematics is simple, it is only because they do not realize how complicated life is. ~John Louis von Neumann

You must have noticed that whenever mathematics starts becoming easier, one or two brain hacker questions just blow away your interest. Now if work harder, and develop creativity in your mind, these brain hackers will turn to normal questions automatically. Whatever you here or learn, try to feel it (isn’t it funny). You must always have your own opinion/logic for a particular theory or problem which will help you feel confident in your approach.