you shouldn't really listen to people that brag about conversion ratios and hit you with a referral code... conversion ratios are called that way because they vary from the floor to the roof. an example: 5 months ago i was converting a sponsor 1:400 (tgp traffic, my exit stats so that i could be sure about the real ratio). right now it's 1:2000. what i did was to switch to another sponsor and am currently 1:320.
the only good way is to test everything yourself. go there, sign-up, send 5000 clicks and see how are the things going. if get a satisfying ROI - stay there. if not - move your traffic again till you find someone who delivers more than you spend
