Ask HN: How did you improve your problem-solving skills?

I'm currently trying to get better at solving CS/Math puzzles and I'd like to hear your story - what are you doing when you struggle with problems from Project Euler, HackerRank, LeetCode, etc? What kind of resources helped you? Did you read "How to Solve It?" by G. Polya? If so, do you think it's useful for non-mathematicians? Thanks for any hints!