So why do we need to get a clear picture of the "ideal fish" (or customer).  The main reason we need to know this is because everything else depends on getting a clear understanding of that fish. If you're having trouble finding the clear picture of your fish then do some research.

a) Ask friends and neighbors who are prospects of your product.
b) If you already have a site then conduct a survey / research with your current customers.
c) Ask some of your competitors - don't be surprised if some folks won't share things with you but you will be surprised a few will.

If you can't get really narrow, then get as narrow as possible (till tomorrow anyway, then we'll turn things upside down a bit).

Tim