I believe that if I look after the people who appreciates my work they either come back for more or refer me to their family and friends. One way or the other, it's a win-win situation for me.
In my little craft business, I rely heavily on repeat customers so I make sure that every single customer is special. It's not rocket science. Simple things like responding to emails promptly or keeping them up to date with the progress of their order can make a big difference. Do you ever get annoyed when you get email updates on the progress of your order? Of course not. Everyone wants to find out what's happening.
The other thing that I feel is also very important is posting the order as soon as the payment is received. I don't have a "posting day" or a standard postage turnaround time. If I have to go to the Post Office everyday, then so be it. We are all excited with our purchases, no one wants to wait for long.
Sometimes I give away little gifts or extras especially to my valued customers. No matter how little it is, you'll be surprise how much it is appreciated. There are a lot more things you can do, to make your customers special. Want some ideas? Just put yourself in their shoes.