Designing the right incentive scheme

Some basic rules for an incentive scheme, as offered in 'Think Like A Freak' by Steven D Levitt and Stephen J Dubner:

1. Discover what people care about
2. Choose something that's valuable to them but cheap for you
3. Pay attention to how people respond - and learn from it
4. Create a cooperative incentive, if possible
5. Appreciate that some people will try to manipulate your scheme