I suggest Simple Chess by GM Micheal Stean ,The Ultimate Chess Puzzle Book by GM Emms and 100 Endgames You must know by dela villa
You can also alternate every other day by doing 2 hours of playing and in the next day 2 hours of chess study.
I suggest 30 minutes tactical study and 40 minutes playing the games in the Stean book. And 50 minutes playing chess.
The next day you can do 30 minutes tactical study.60 minutes of endgame study and then 30 minutes playing chess.
The next day you can do, 30 minute tactical study. 60 minutes endgame study.
You can alternate these.
Well, I'm no grandmaster, but I try to go for a well rounded game. I think you have to put in daily tactics study. I recommend Preuss' videos on "Becoming a Tactical Genius." This is a very comprehensive study program for tactics. After watching it I do at least 15 minutes of tactics training daily. I also like to delve into the chess.com videos and follow a series on a given opening or theme. I recommend the early Danny Rensche Pawn Structure series as well as his endgame series (all of them).
To sum up: use the videos. 1. Tactics with Preuss - (if you follow his advice do 15 mins. of tactics training every day). 2. Openings of your choice. 3. Pawn structure with Rensch. 4. Endgames with Rensch. I try to balance my study between tactics opening and endgame.
Hope this helps.