I haven’t tried it yet, but I suppose one should be looking for areas where people are ready to use their credit card, e.g. when people are actually looking for something where they are set for buying something. This is why I think casinos are great, because almost everyone looking for an online casino is ready to spend a dime. But there must me other ideas, e.g. like coupon codes where people have probably decided to buy something, but now they are only looking for the right place to buy it. Samething perhaps for mobile subscriptions etc. But on the other hand I would never be looking for a place to buy beer online, so if I where to advertise for beer it should be on a pay-per-click basis (or perhaps post a blog post about beers to get a couple of tasting samples).