You can also search (in google or yahoo) for “advertising” or “free advertising” or “paid advertising” and so on. Then go to those sites and advertise your invitation link/page, either for free or pay them to do it for you. If you pay them to do it for you then it is quite PASSIVE.
Get the js Guide to Autosurfs, Surfs, and HYIPs and win with these most of the time! Understand the mentality of the Operators/Owners and the Players. It is updated almost daily! So go and pay and read and play.