It took me about a year to become an Expert, which may be a small feat, but I still believe that maybe sharing the resources which I personally had used might help someone.
For learning algorithms: You can use a channel called takeuforward by a guy named striver: https://www.youtube.com/@takeUforward. The guy has excellent explaining skills. I would ideally recommend building a habit of reading blogs and articles, as later on, you will only have those to help you.
For practice:
CSES Problem set: It's a very great website to practice good quality questions. The questions are sometimes standard and sometimes very unique so you ultimately end up learning a lot but the time constrains can be a bit irritating tbh. https://cses.fi/problemset/list/
TLE eliminators cp-31: Best one I found for rating wise practice although you will need more than 31 questions generally to get comfortable with higher rating but it does provide us with all the necessary concepts and algorithms related to that rating. https://www.tle-eliminators.com/cp-sheet
Codeforces Problemset: Just put in the rating you want to get comfortable in and keep on making it green until you can comfortably solve at least 8/10 problems without any help. (probably the one which will work for everyone)
Always upsolve the contests and if you are unable to find you're weakness then maybe try looking at the contests where you got a negative or very low rating change and see work on the topic of the questions which you were unable to solve or solved too late.
Give as many contests as you can provided you have time to upsolve them later. Some other sites where I give contests are: -Atcoder -Codechef -Leetcode
Most importantly enjoy the process always remember rating is a by-product not the main goal.
