deals fall through

defer. don't spell out all your intentions before you need to, because it's possible that the other side has other ideas that are even better for you than what you were thinking about.


know everything you can about your position, about your alternatives to this deal, and about the boundaries between when the deal is bad enough that it would be better for you to walk away.

know everything you can about their position (know, or try to make informed guesses about the same things that the previous sentence said to know about your position)

know everything you can about the subject of negotiation.

don't give information when you don't have to. when you make an offer, as you make the offer, reference some information that supports why this is a good deal for them and possibly why you can't do any better. after making an offer, wait for a counteroffer; try not to make an offer, have the other side say "nope, my offer is the same as before", and then just get nervous and raise your offer. don't seem desperate (which also implies, try not to place yourself in a situation where you are desperate, and then must negotiate).

it's good if you let the other party make the first offer, but on the other hand, don't be afraid to initiate discussion, and if you do, say something more substantial than "so, do you have any offers to make for me? i'm listening".

the best way to have a great outcome is to have a good alternative to the deal under discussion, and for that alternative to be credible i.e. you can prove to the other party that you have this alternative and that it's a good one (the canonical example is when you are buying a car, if you have a written quote from another dealer that is low). this way, you are willing to walk away and the other party knows it. This does not mean that the other party will agree every time, but it does mean that if you walk away you will still be happy.

do go ahead and try to be friendly and build a rapport with your counterparty. do be open to creative, non-zero-sum ways of improving outcomes for both of you. but otoh do listen if a little voice inside you says that the other party has something up their sleeve. do watch out for deals that are too good to be true, and try to think about what would have to be true for the other party to selfishly benefit from a seemingly unbelievable offer. do take the other party's offer home and consider it rather than negotiating on the spot. do allow time for negotiating to drag on; if you are more eager to close the deal quickly than the other side, you are at a disadvantage.