I never promoted click bank products but it should be the same as all other offers I'm running.
The thing with bb is that it will work only with products that have massive popularity and people are directly looking to buy it, not just information about it, for example you choose product that called - 'Black Tea Diet' then if you will target this exact keyword then you won't have much success cause you may attract clicks from people that simpley looking for reviews, more info and all kind of that shit, you should target keywords from people who already want to buy the product, like - 'buy Black Tea Diet', 'Black Tea Diet discount' and such.