Whether you’re a salesperson, an operator, or a businessperson, if you can understand what the other person is thinking and what their goals are, you can reverse engineer those aims and map it back to your goals too. That knowledge sets you up to win. You’ll both win.
Sell something. If it’s a product, make sure its quality, then sell it at a fair price, and make sure the breakeven point is doable for you as the business owner. If it’s a service, make sure there is added value, as in you are very good and knowledgeable in your field, and the service provided is unique, at least in your market.