Spend nothing, at first. The first thing you need to do is create an "engine". Something where you can reliably introduce a user to it, and have that user ult

Spend nothing, at first. The first thing you need to do is create an "engine". Something where you can reliably introduce a user to it, and have that user ultimately invite at least 1 other user (on average). In modern hype-infused parlance, this is a "viral loop" (with a viral co-efficient of more than 1). But really, it's as old as the Internet. You can achieve this in one of 3 ways: 1) Be surprising, controversial, funny, or useful. People always tell their peers about fabulous products. 2) Get scientific about viral marketing. Widgets, facebook apps, etc. This is hard for most businesses (but for others-- it's laughably easy... I know a guy who is serving up hundreds of millions of widget views on a product that essentially didn't evolve past the first 20-30 man hours of work). 3) Get smart about SEO (if your biz is a content play). This is really just a different flavor of viral marketing. Yelp, Digg, and other UGC sites have a great viral loop. Visitors come. Some create content. Content gets indexed. Indexing generates google traffic for new page, which brings in users. Rinse, repeat. Wait 2 years and you have a vast pile of indexed content. If you can't do these, then you're stuck buying attention with time or money-- which scales VERY poorly unless you have a great opportunity for revenue/profit. If you can pull these off, then marketing dollars/time is just adding gasoline to a healthy little fire.