Who told you this was a good business model to earn revenues? You might want to do something that you love and not something you think will work... Passion = Profits Do what you love! the money will come.....
My Dear Adsense income is based on clicks, so the more users you have, the more page views and more chances of clicks. So you may try to get maximum users registered, who visit your forums regularly and for that you have to make sure, you have good quality content. If your forum is search engine optimized and you have maximum numbers of pages in Google. Your Adsnese income can increase. Because the traffic you get from Google is keyword based and when users will come to your site from Google for some specific keyword, they will find relevant Google ads on yours pages and it increases chances of clicks. So work on 2 things. 1- More users 2- Search Engine Optimization Regards,
1. Try to get a forum system that enables you maximum control over design/templates so you can: 2. Optimize for serach engines, to increas traffic 3. Optimize design and ads positioning, to increase clicks. Other than that - get as many quality users - people who write well. And try to keep the forums focused on topics that attract good adwords. You can find tons of info about how to do all this in DP forums and the web. Have fun.
Adsense on forum is a challenge.. you may want to try out some referrer contest to increase your traffic initially.