How to incent a contractor

[Brad Morse]

Does anyone have any proven best practices to incent a contractor to deliver a project on time and at or under budget? I have a contract in place with a payment schedule, but would like to incent him to go above and beyond to ensure that it's hit or that money saving recommendations are provided.

I'm thinking about some kind of bonus back to him. Say, 50% of the savings he'll earn on top of the contract?

Thanks for your input!