When I get frustrated about the difficulty of finding new customers, Rob May is a good person to help me get over it. Finding customers is one of the riskiest, most expensive, dangerous activities that a company undertakes. When someone tells you that you just have to keep your nose to the grindstone and meet more people--they are wrong. If you don't find the right place to meet those people, you will never have a sustainable marketing model.
Coconut Headsets: Customer Validation, 2012-Feb-21 by Rob May
Remember that your goal as an entrepreneur is to deploy capital effectively, and one of the most effective ways to use capital is to de-risk the business. This means investing in areas that help you learn about the market. The riskiest part of your funnel is the top of funnel, because that is the part over which you have the least control. Let me say that again. Focus on top of funnel the most, because that is where you have the least control. Your customer acquisition options are largely external and dependent on market structure, thus they are out of your control. Your conversion rates once users hit your site are primarily internal and under your control.