Advertising a new forum


So I found a way to get many members with cheap advertising, buy paid to click from ptc sites, but to only allow North American users it will cost triple, so most of the traffic will come from Russia, Brazil, etc, however I only did a test ad on another forum I have, so what niche would you suggest for ptc users? Most of them are looking to make money, so I'm thinking of starting a brand new forum, fill it with 200 article on how to make money online, and advertise on ptc sites.

But my question is, to get max users for my ads should I do a forum on "how to make money online" niche?