Chess Improvement

I think you’re honestly looking at it from the wrong angle if you are looking for 10 things and then ranking them. Chess layers things. Let’s take endgames for example. I’d begin with teaching basic checkmate patterns and key theoretical endgames. From there, there can be layering to tougher endgames and eventually some really advanced ones. They all build on each other and no one ever really “masters” endgames. It’s something you layer over time. You’re probably best to just learn a little of everything until proficient for your rating level and then layer onto that foundation whenever needed.

If you want to improve at chess, it’s mostly playing games and analyzing them (immediately after if possible) and chess puzzles are good to get into a routine of solving as well. You should eventually learn key endgames and many other patterns and concepts, but that can happen over time.