Tips to practice and improve?

Hey everyone. I like chess, but so far I am only a casual player, I play a bit on lichess but I don’t even have a rating yet. And I don’t know all the openings. I know how each piece is allowed to move and try to think some steps ahead, and that’s all, and it’s enough for some casual fun.

However I’d like to improve. To know more about chess strategies and theories. What materials and resources do you recommend? Maybe chess books? YouTube channels? How did you learn the concepts and improved yourselves?

Thanks in advance.