When you are trading no one will give you a good deal if you just plain or mad you must be positive. Positively nice no matter what because if your nice to them tell will be nice to you and will help you out. Most people if they had a bad day or just was trading with plain old people you might get bored and discomforted, with a positive attitude they make you good offers instead of the other guy because he wants respect what the other traders won't give him.
Start off by giving a offer talk to them make it so they want to trade with you just talk. People won't just give money away they want someone to talk to.
Once you talked for a bit tell him you'll make him a good deal explain that he'll make profit. Be convincing enough so that he wants to trade with you not the other's