I'm not sure of your background, but I've become more successful as an affiliate by joining some affiliate marketing sites and by listening to advice from those and these forums. Little things like how to attract customers to your affiliate shop, how to keep them there and not distract them with other things. Something small, like Adam telling someone they need a "call to purchase" and I asked him what he meant. He suggested that on my WishAds, I had something like a "buy now" button option, as well as things like showing the product instead of the design.
There are tons of things like that that I've implemented and plenty more that I haven't, like using the getclicky.com API to better track my customer all the way to the sales cart.