After realizing event ticketing is quite the classic commodity, I asked myself, how can I differentiate my offering? I can't compete on features, service fee kickbacks, venue relationships, etc. So I built a guestlist component and targeted it directly for nightclubs. And so, after a couple failed fundings, working with crap people, I had a great product, a couple loyal customers, poor marketing. I've spent (am spending) tons of time to clean up the company (get it down to just me, no overhead, etc) - I've dropped the whole 'startup thing', now I'm building a SaaS company for myself & my customers, and see where it will take me. I prefer the freedom and debt-free lifestyle of living that it affords me, over being a CEO of some venture funded company.
But to really answer your question, I got my first (SaaS) customer by hanging out every night at nightclubs, getting a couple people to evangelize using my software through the beta's. Once it was good enough, such that I didn't have to do anything for the club to operate itself, I went to another nightclub and just sold them on it. It wasn't that hard because the product is good. The clinching feature in my case is the ability to add a guest to the iPad via SMS - promoters love that. Now I am trying to figure out how to scale up my efforts, see if any partnerships make sense, maybe move geographically (I'm in Vancouver, but American)