Give extra features. Do the first project cheap. And whatever was in the spec, add at least two new cool features. This BLOWS AWAY the client. Don’t forget the client is a human, not a company. That human has a boss. And that person wants to look good in front of her boss. If you give her a way to get promoted, then she will love you and always hire you back. Don’t forget to always give extra. A simple effort will get you a customer for life.