[Atiscant]

I suggest you start out with a course or book on formal logic in computer science. In particular doing proofs in intuitionistic logic. You can use a simple proof assistant to verify your proofs and it will help you really understand how proofs are done and how they are just a kind of programs in a special programming language called mathematics (given some assumptions). Proofs in higher level books are all informal, so you can’t do them programmatically in most cases, but it really helps with understanding how proofs works. After that, follow what subjects finds your fancy.