improve the nimzo

Study some grandmaster games with it.

Studying books on the nimzo that contain full games annotated, like Emms's Nimzo-Indian Move by Move or one that I cannot think of the name or author (First name is something like Christof, maybe - Red Cover and Everyman is the publisher).

To piggy back off of post #3 the Christof Sielecki book is on the Nimzo Indian and Bogo Indian and there is a Nigel Davies book on the Nimzo Indian and Queens Indian. Both books are in the opening repertoire book series.

Is there something wrong with the Nimzo?

Here is a Gukesh win from the Toronto 2024 Candidates' Tournament.
https://www.chessgames.com/perl/chessgame?gid=2693493

"Draw boy" Abasov created an interesting dynamic in the Candidates Tournament. He was clearly of lower class of play to all the other players, and happy to get draws white or black. Gukesh was able to get a fighting game with the unusal and probably unexpected 4...h6, essentially won the tournament by winning. Nepo wasn't able to win with against same opponent with white or black.