You should have a solid theoretical basis in case you want your practical activity to be a good one. The best way to understand the theoretical concepts of Texas Hold'em is to read books on this topic. Still it is necessary not to choose a wrong book.
Nowadays, with the tremendous spread of poker, it seems that every second person writes books about the game. All of them would call themselves 'poker-gurus,' 'poker experts' etc. So if you are trying to choose something to read on this topic, it is very difficult not to be drowned in the vast ocean of literature.
But if a person hasn't ever won a single major tournament, what does he know about the winning strategy. But as in every sphere of human activity, there are good practical players as well as famous theorists and in poker. You just can't understand the process of the game if you haven't read some books by the most authoritative poker theorist David Sklansky or "the father of modern poker" and "America's Mad Genius" Mike Caro. These people are living classics, though they aren't famous winners. They are famous coaches.
Always try to choose the books by the authors you know about.
So, enjoy these pieces of knowledge and improve your game.