I study opening books. Not the best way to study chess but they are practical when you play someone in your opening and want to learn more about the variation. Here is a good link to some chess books which are all free. Here is my French Defense Study which is more of a theory book and here is the first part of my Queen's Gambit Study which is more of an explanation of the opening with some theory and shows some sample games.
One coach on chess.com told me to do a lot of chess puzzles and try to improve the middle game and endgame. That is where the most improvement is made. I am trying to read "The Woodpecker Method" which helps with this so check it out
Does anyone out there have a chess study routine? I can't go up anymore