I use to promote a trading site that allows us to use our own affiliate link. The result on how many will sign up on your affiliate link depends on yor exposure. If you don't have enough post that others will notice then there will be low sign ups using your link. In terms of payemnts from affiliate link it depends on the site how much you will earn because sometimes you get a cut from their (referral) deposits and sometimes you dont get paid right away, you need to request for it to be transferred to your main balance.