I suggest doing lots of problems. Here are a few excellent resources that concentrate on teaching "problem solving" in math from the ground up: + Brilliant --

I suggest doing lots of problems. Here are a few excellent resources that concentrate on teaching "problem solving" in math from the ground up: + Brilliant -- https://brilliant.org https://brilliant.org. Fun problem-oriented introductions to specific math areas. Their "explorations" are designed to help you think about problems in new ways. Brilliant also gives you a weekly problem set of beginning-intermediate-hard problems. You can even practice writing proofs by writing solutions to new problems. + The "Art of Problem Solving" books. Advanced high school, but has really great insights and lets you practice common math patterns you'll see later. + The "Book of Proof" book. Gentle introduction to proofs. An introduction to fundamental higher-level math. + Project Euler -- https://projecteuler.net/ https://projecteuler.net/. For getting better at programming and math together.