How to make a sucessful ad campaign?

Hi, I've been trying IM (banner advertising and SEO) for a while and haven't had any luck and I think it's because I try a lot of different things at once.

I decided to stop spreading myself thin and focus solely on advertising since I just don't care for SEO. I was wondering what approach someone who makes $8/hour should take? I bought Media traffic meltdown which went over using banner ad networks like project wonderful and BSA which gave me a great push in the right direction but I have trouble coming up what a demographic I might want.

Project wonderful, for example, I have no idea what people reading webcomics want and I kinda have to since that is a good majority of what they offer. I tried looking up demographics via sites like quantcast, but 75% of the time they're blocked by the owner.

I guess my question is how do you research and know what to offer various demographics you encounter? Would spending a (probably) steep sum for mentor-like help benefit me or just struggle and learn as I go be more beneficial? Thanks for any help in advance, been reading these forums for a while and always liked the great advice, thanks to anyone in advance!