I don't recommend in your case reading any opening books, nor studying games of the "old masters" like Morphy, Capablanca, Alekhine. Why? They are too difficult for your level. Let's be realistic. You need to be very good tactically and have good endgame expertise to make similar moves in your games. Watching videos on youtube is a waste of time, because those guys are on expert or master level, play bullet only and talk jokes to make kids watch them longer.
In my opinion what you should do, is to watch games of players 100-200 points higher than you. Learn how they play, see what works and what does not. But don't make their mistakes - you can use the computer analysis after the game to see what was bad. Analyze all your games. Don't play a new game untill you analyse properly the previous game. Work on tactics! Your puzzle rating is 800. Your priority should be to raise it at least to 1500. Do it regularly. Every day!
In my opinion what you should do, is to watch games of players 100-200 points higher than you. Learn how they play, see what works and what does not. But don't make their mistakes - you can use the computer analysis after the game to see what was bad. Analyze all your games. Don't play a new game untill you analyse properly the previous game. Work on tactics! Your puzzle rating is 800. Your priority should be to raise it at least to 1500. Do it regularly. Every day!