What do you think is better while advertising?
1) Making a fixed campaign with 0.2 per month for 5 best quality posters, min requirement only 20 posts , so something like 0.01 per post.
2) Advertising in bitcointalk with banner ads, with only one slot for 1btc per month.
IMO signatures are better because you get better visibility.
Ofcource signature compaign are better because of many reasons--you will pay much less then 1 btc per month combing all the users if you have member to sr member level only..secondly your advertisement will be much visible in various topivs so better advertising..But the best thing you can do is to provide a signature compaign that pays per post not fixed and that pays weakly,this way i am sure you will get more participants.