In Paid to click sites you can earn some amount by watching the ads of other members and then use it to promote your own link.
Much easier will be to invest few bucks in promotion and to get few thousand hits to your links.
The truth is mall number of people from that sites will join. The only tactic is to target premium members or tier one traffic from countries like US, UK, Australia etc. The other members only clicking ads for cents there, so you cant expect some investments in business from them.
The most popular PTC sites are: