For me, offering free money to register as our referral is effective to get number of referrals only but it wont be effective to get referral commission or to get real gamblers as referral.
I myself tried to get referral on some casinos by offering bonuses for signup. It was effective and giving positive results a few years ago. I had gotten some real gamblers as referral on a different casino by using this method, unfortunately they have closed their business. But I haven't gotten the success with this method on Stake. I got only 1 referral who place bets with deposits at Stake occasionally. A few other users only placed some bets with the tips which I send them for creating an account through my affiliate link, then they never made any deposits.

Never offer signup bonusses for referrals, because they just signup with a throwaway account to claim the money and then they go inactive.
I tried this before with other websites and it cost me more in paid bonusses than what I gained through their referral commision.
