When I teach, I stress the ideas of two of the greatest players. I stress Capablanca, because he had the unique ability to know exactly where his pieces belonged. And I stress Nimzovitch, because his concepts, if not his play, provide a way of thinking about the game that is very instructive.
Aron Nimzovitch's My System is widely recognized as a classic of chess literature. Part one covers the "elements" of chess, part two reviews Positional Play, and part three provides 50 illustrative games. The modern edition (edited by Lou Hays) provides algebraic notation and more readable English.
If you sincerely want to improve, I wholeheartedly recommend that you study parts two and three. To make your job a bit easier, I provide all of the games in part and one of the illustrative game below.
1.e4 e6 2.d4 d5 3.e5 [3.Nc3] 3...c5 4.Qg4 An innovation by Nimzovitch, but not best. 4. c3 4...cxd4 5.Nf3 over-protecting e5 5...Nc6 6.Bd3 The queen, developed perhaps too early, restrains the development of the black kingside. 6...f5 7.Qg3 Nge7 8.0-0 Ng6 9.h4 Black is untangleing, but this move (with the threat of h5) prevents normal devekopment with Be7 and 0-0. 9...Qc7 10.Re1 Over-protecting e5, confident that the space advantage offered by the e5-pawn will permit him to recover the pawn he ascrificed earlier. 10...Bd7 Not impressive. Bc5 was needed to complete development before the h5-Ne7 move pair. [10...Bc5] 11.a3 0-0-0 12.b4 [12.h5 Nge7 13.Ng5 Re8 14.Nf7 Rg8 15.Nd6+] 12...a6 13.h5 Nge7 14.Bd2 h6 15.a4 g5 16.b5 f4 17.Qg4 Having secured e5, white is in full command 17...Nb8 18.c3 [18.Nxd4 also wins easily] 18...Re8 [18...dxc3 19.Rc1] 19.cxd4 Rc1 is coming 19...Kd8 20.Rc1 Qb6 The black king cannot move... all white needs is check 21.a5 Qa7 22.b6 Qa8 Add a bad queen to black's woes 23.Rc7 Brutal. 23...Nf5 24.Nc3 Be7 Diagram