What teaching or training tools are out there for a very average player at no limit Texas hold’em who just wants to get at bit better to a respectable level at a modest time commitment , and does not need to be a pro-level player?
The odds are a small part of what you have to consider.
If you want to quickly improve to a proficient level there's no quicker way than to read Theory of Poker and Hold 'em for Advanced Players. Both of these books focus primarily on limit poker, but the concepts are critical for no limit as well. And you'll realize there's a lot more strategy and nuance in limit poker than you thought.
Modern Poker Theory as mentioned by the other reply is good. I'd also suggest Play Optimal Poker by Andrew Brokos. The former outlines a lot of strategy in the game and talks a little about game theory and its implications. The latter gives less direct poker advice but uses "toy games" that share some similarities with poker but are simplified to demonstrate some of the implications that game theory has on poker. It does contain some direct poker advice but it's more of a book to teach you how to think properly about how game theory applies to poker and how you can use that to study with something like a solver and actually understand what you're seeing. I would suggest you pick up both, I think that the Brokos book assumes you know certain poker terms and doesn't contain a glossary whereas modern poker theory is almost like a textbook and has a section where it defines all of the terms it uses. Modern poker theory will have more actionable advice but the Brokos book is excellent to teach you how to think about game theory and requires more self-reflection and has more questions to the reader.
Applications of no limit by Janda or mathematics of poker are recommended by a different reply here. I would caution that these are extremely academic and extremely dense texts that would be a very tough read for a newer player. Mathematics is less practical and more of a math book than a poker book and applications is Janda showing how to work out solver-like solutions before solvers existed and also contains a lot of math. I think the other two above are more practical and aren't going to lead you to put the book down a 10th of the way through.
The Mathematics of Poker, by Chen & Ankenman - this one doesn't age because it's really fundamental if you want to understand things from the ground up. But it won't seem that practical at first.
Applications of No-Limit Hold 'em, by Matthew Janda - this one goes into specifics about how to think on each street, how to build a good strategy etc. Some of the details will be different from the latest theory because the book was released in 2013 but it's still a very solid read if you want to level up.
If you like video content, the Daniel Negranu Masterclass is extremely well done. Phil Ivey also has content on that site but I found it much less comprehensive.
After that, perhaps watch some Doug Polk on Youtube to see how he uses the concept of putting people on ranges of hands and what his thinking is in a specific spot.
Training sites are probably going to be your best bet to improve quickly. I see Run it Once was mentioned. I've personally used Upswing Poker in the past and they had some great resources. Bart Hanson's Crush Live Poker videos are great too but I can't vouch for the training course.
