How Do I Learn?

I always wonder how to approach the study of a subject, such as Mathematics, for example. I want to self-learn it, but I'm unsure of how to begin. Which books should I read, and where can I find them? With hundreds of books available, I aim to learn in a sequential and progressive manner, starting from arithmetic and progressing to the graduate level. Similarly, for biology, I am uncertain about where to start and how to proceed. What books should I read to cover the subject comprehensively from beginning to end?