Ask HN: Sales strategy for a custom software startup

We're 6 month into a custom software startup. The business model is simple: make from scratch a software for a medium company, develop constantly and charge monthly. It worked great for me as a freelancer (and for my customers as well) and I'm trying to scale it together with an investor (former customer who got rich).

The technical side is ok, in about 6 month we have a good team and a couple of more apps. Last month we really started to look for new customers, but it goes a lot more slowly then expected. We have two big problems: First is the way we approach a new client - I dislike spam in any way and most things we can try are email/phone/snail mail spam. Also they don't work very well. The other is the difficulty of explaining the concept. Some like both the idea of custom software and of selling is as a service, but most find them too foreing.

Any ideas on future sales strategy?