I read this interview with competitive programmer Ahmed Aly: Why Renowned Googler Ahmed Aly Chose HackerRank and what really stood out to me was his advice:
Ahmed, what advice do you have for people who want to become great programmers like you?
Don’t try to solve harder problems unless you are really good at solving the easier ones. That means solve a lot of really easy problems (that could be hundreds), that will improve your coding skills, which should be the easiest skill to gain. Then go to little bit harder problems, and so on.