This classic classic sales technique book is about the negotiation part. I think it reduces well into a simple How To list. It’s worth reading the examples as anecdotes, but the world really needs a Do and Don’t list for these People Topics.
Eg – never offer or accept to “split the difference”. Saying say just declares you were playing with a chunk of margin.
The rest —
beta.knotable.com/p/RAcPUN/Negotiate_anything.