Advice: Rewards and Punishments

I'm interested in exploring punishments and rewards, but I am not really interested having a rule set. I'm worried about creating a sense of obligation by attaching rewards or punishments to specific acts. I'm mostly seeking thoughts and advice. the best solution I can think of is to create a "pass/go" system (like wearing my collar to indicate that I am open to receiving rewards/punishments at the whims of my dom) and creating a list of example circumstances for what should be rewarded/punished without creating a hard and fast rule set.