For me 'Getting to yes' was too idealistic. It is a classic and good starter but did find it that usable for me.
I was impressed though by radical approach of Chris Voss on 'Never Split the Difference'. Author is a former hostage negotiator, so there are also a lot intriguing stories included w high makes it a great read.
If you want to get your feet wet with a short writeup online, I found these two blog posts (part 1 and 2) to be extremely valuable. It does a fantastic job of making sure you're mentally framing the situation correctly, which makes an enormous difference.
