I have launched a make money online. I have few people registered and they made some posts. Also I pay them to post. What is the best place to advertise a paid forum?
other forums. Participate in other forums related to your topic and add a signature. Don't post crap though just to get your signature up. Post useful material that will generate discussion. http://www.talkgold.com/forum http://www.warriorforum.com http://www.sitepoint.com are all good to start with
Make it unique to stand out from established forums like this one. Offer contests etc to attract people.
Give some freebies to your members! I own a make money online forum and I'm offering a FREE report on How to make atleast $45/day to my members. This method worked very well. Also try to give some useful content at your forum, so that you'll get returning members! All the best with your forum! Some times SEO too work!
How about a monthly giveaway? For the best ideas, most viewed topics, blah blah blah. Another possibility is (if you're using AdSense) to do a similar revenue-share as on DP. You could also encourage people to link to your site by changing the ID code in adverts to theirs every nth time a visitor comes from a link on their site. It literally costs you nothing.