Pick up a copy of the tried and true, "How To Win Friends & Influence People". The rest of the fad business books come and go, but this one is a great start to learn how to interact with people when you're trying to sell them on "something".
Here is the most important thing about the book. The basic motivation for all people is to feel important, you can influence people by making them feel important.
But also hint at your ability to withdraw that confidence in someone if they don't live up to your expectations. Talk up someone's abilities while showing your high hopes in them are conditional on their actions.
