For dommes
If you want to give a task/punishment for a sub, it should consist of what he likes + a little more. For example, you have a sub who's into feet and you tend to sell feet related items(like socks, shoes etc), for the task/punishment, you make him buy more than what he used to buy(if he usually buys 1 pair of socks, make him buy your shoes/footwear in addition to that/ make him buy you a new shoes that he gets to buy that later if he behaves well), not asking him to do something he doesn't like, like licking the toilet seat etc.