For the lame definition of valuable: if you are not in the practise of negotiating, try to negotiate in more situations and see what happens! Attempting to negotiate will not harm your situation when dealing with another party making you a genuine offer. Even if you are a very mediocre negotiator, you might be able to easily eg obtain a somewhat higher salary when starting a job versus just accepting a given offer if…
I think "Never split the difference" by Chris Voss is the better book if you can tolerate a bit of bragging.
There's also a Farnham Street podcast with Voss: https://fs.blog/2018/01/chris-voss/