Ask HN: How do keep track of potential and existing customers?

When starting up a lot of the work involves dealing with all kinds of people like customer leads, people who are using a trial and real (paying) customers. How do you keep track of them all? I'm looking for something that where I can keep everything organized in groups. I looked into Highrise but it doesn't quite seem to be what I'm looking for.. Suggestions? How do you do it?