The key to having a successful business is to attract customers cheaply and then quickly monetize those customers at a multiple of what they spent to acquire them. At least according to David Skok from Matrix Partners (and investor in HubSpot) - that link is to an interview in the Wall Street Journal.
Too often startups make their strategy too confusing and complicated. This is because they don't have the answer yet. Most really successful businesses have a pretty simple model at the core. Google, Ebay, Salesforce.com. See?