Ash Maurya ( @ashmaurya ) has posted a very interesing Post about the 10x Product Launch. http://www.ashmaurya.com/2011/10/the-10x-product-launch/
This captures some of the key issues around building a business. As you progress through the stages of different numbers of customers, you shift and need to use different tools and different focuses. When you are just starting out, you have zero (0) customers. At this point, your goal is to get one (1) customer. When you have one (1) customer, your goal is to get to ten (10). The task and process of getting the first customer is very different and more personal than getting the 10th. By the time you get to the 100th customer, you have enough data and enough history to be able to automate your processes successfully. It is always a bad idea to automate processes which you can not accomplish by hand for the first few cases.
For your first 50 customers, you should definately be working to talk to them in person. This does not mean you can't use surveys or email or ads to search for and find potential customers. But it does mean that you should get out of the building and talk face to face to them early on in the process.
As you begin to see the patterns, you can then focus on the area where you are most likely to make traction.