(For background, I'm a faculty at Carnegie Mellon University in the Human-Computer Interaction Institute) For best books, it depends on if you want to understand users or do implementation. But generally, I'd highly recommend Don Norman's The Design of Everyday Things to improve how you look at the world, and Steve Krug's Don't Make Me Think for simple and practical design tips. For tools, the best is paper prototypi…
If you haven't guessed already, my background is engineering. So you read from that what you want, but I've crossed paths with a very large number of engineers who dismissed or diminished their own ability to form judgement on UX because of a general sense that the "consensus" was that engineers aren't good at that, and have seen several cases where the decision model in organizations was specifically tailored to tune out engineers from UX decisions. Both of these things are wrong from my pov. I certainly don't want to diminish the value of having UX as a specialization. However, I cannot recommend a title whose narrative champions one set of professionals at the expense of others.