Lets consider what they have in common. The Internet is a PULL medium. The first step is to attract a prospect. The second step is to convert the prospect into a customer. The third and most neglected step is following up with your existing customers offering additional back end products to existing customers.
Customers make better prospects than non-customers.
They are the cheapest prospects to reach. The easiest sale will always be to an existing satisfied customer. I think the number one reason why so many people get confused about marketing is because the blind are leading the blind. Everyone wants to be an expert or marketing guru. They think that acting like an expert makes them one.