Performance bonus

Can anyone give some insight on how to structure performance bonuses to hourly employees. We are trying to come up with a bonus incentive for our employees to reward them for bringing in new customers, making sure our current customers are receiving the best of their abilities which hopefully makes the work more profitable, and at the same time give them a reason to work with us rather than just for us. I can see this being a little easier with a salary based employee but hourly. I look at the possibility of call backs, overtime, & so on that can cost me money while at the same time allowing them to already collect their bonus while cutting my planned profit percentage. Any help is appreciated.

Thank you