Good article. A lot of the comments here give bad advice though, which isn’t surprising because they show a lot of common misperceptions about chess. Jeremy Silman has written a couple of books about what is actually important. Quickly, what worked for me when I started playing on chess.com at age 40 after not playing for over twenty years. My rating at age 17 was 1450. Restarted at 1200, and barely progressed at first. If your rating is different you may need different things. Again, Silman is good on this. What worked:

1) eat. I would start playing in the morning, do okay, then lose a bunch. Finally, realized my blood sugar level was a major contributor to my elo 2) study tactics. Chess Tempo is great. Lots of good tactics books. Especially study spotting threats 3) Study basics of positions: best places to post rooks, bishops, control of center. But tactics more important. 4) don’t spend much time on openings. Learn the basics of a few common ones. Games will quickly diverge from openings. Because GM games so often depend on openings, amateurs (like me) tend to overpivot on this. 5) After playing, load your game into a chess engine and analyze what went wrong (if you played perfect, analyze what your opponent did wrong). Until about 2000, whomever makes the fewest mistakes usually wins.