Startup Tip: How I grew Mint's waiting list to 20,000+ (opens in new tab)

In the spirit of failing early, this is a great way to figure out where people really what what you think they do. If you can't get a few thousand email addresses, you quite likely have a bad idea or haven't figured out how to talk about it yet.

a) some sites dont need outreach or trust to be built since their initial users could theoretically spread the product

b)you want to build the relationships and things earlier than you need them.

Solve a problem and find the people to whom that solution is most valuable. Start there, cater to them, make them passionate, and voila: there's your base!