How about selling a useful product.

start off with asking your client if they are happy with their current software. If not then find out why. If so, then ask if their current software is missing anything in particular that they would like. Hopefully your software can fill those gaps. Then tell them the benefits of your product and give them specific examples. If their current software actually satisfies all their needs, then you can't help them, but then you need to find out what software they are using and see if yours even compares. Then you need to use what you learned and add to your sales pitch. The key is to have something that the client needs or that makes his life easier.