What should you never do in a negotiation?

Never make a concession without consideration. Never just make a concession. Give a little, take a little. It must always be a trade, otherwise you lower your own value and that of your negotiation, and you lose. In the case of concessions, try to look at what you can do in modalities or in kind. The delivery conditions, term or warranty. It is essential that it should not damage the value of what you have to offer.