I've never used before any kind of advertising solutions, now I'm with Google's AdWords. I have 50$ in my AdWords account and first of all i need to test the keywords with these money. My website (forum actually) is: http://www.travel-talk.info , if you can take a look over it and recommend me some keywords to promote it on Google I would appreciate that. So far I've used: travel info , travel help, travel advice, travel talk, travel board, travel europe, travel asia ... and that's all. with a 0.12 cents maximum bid and 0.15 cents for two keywords (travel europe & travel asia).
I think the problem with any AdWords campaign you do right now is the current state of the forum. I speak from experience on this as you'll notice I run a travel forum also, but I have no problems with sharing my thoughts, should you find them helpful. I think what you need to do at the early stage of a forum is generate activity. This isn't easy, and requires a lot of hard work, but it's important that if you're paying for visitors that they're enticed to sign up. They're more likely to do so if they see a 'happening' community which isn't what they would get from going to your site at this moment in time. If you created a busier looking place, any visitors you pay for will be more likely to convert (ie. register and post). Even once they do register/post, bear in mind that forums don't tend to make much money. Our own travel forum is more a labour of love than a business venture. Hope this is some help, Aaron