I used quarters, we would allow our son to go outside and pee on a tire, tree, shrub...etc to encourage him to control it at first because he refused to use the potty, then eventually we started with quarters giving him a quarter or betting him a quarter that he couldn't go potty in the potty. Eventually he began uping our bets and loved to spend his money on something he wanted. With our other son, everything had to be a game or a competetion in which he could win, otherwise he would not do it just for money or because mom or dad wanted him to. He would do anything for the babysitter but nothing at home, so we had to create fun potty games that involved competetion, whether it be a race to the bathrrom, who could make the most bubbles, who could pee the longest, who could pee the furthest (obviously, he would have to had another male to compete with), who could sink the cheerios or fruit loops, who could hit the target (a drop of chocolate syrup in the bottom of the toilet)...etc