Raffle thing (Patreon)

So i was thinking about making raffles every month, raffles for both robot lover and Robot acolytes so how the raffles work? to participate on a raffle you must on one of the 2 tiers, the price is a free commissiondepending on the tier you are Robot lover will get a free pic commission and robot lover will get a free anim commission,. The winner cant participate on the next raffle