Be original and have something people want. When vBTEAM started it was just something I started for fun when I first found vBulletin. I had a hard time getting hacks, so I bought a license and figured I'd help others that can't get one. I posted a few hacks and styles on different forums and the traffic starting coming in. .v0id was one of the first members and enjoyed the site and became Admin/co-founder, and here we are, 3 years later.
There are a lot of warez forums out there, so advertising on DDL sites is good for quick traffic.