I believe that the best incentive schemes should be simple in practice, simple to understand and reward the employee. A key to a very successful incentive scheme is to design it to work at team, department, site and business level. Making sure multiple aspects of the business is working towards the same incentive scheme will drive team working and employee engagment.
The end result for the incentive scheme has to be an increase in profits for the business and rewards for the employee as seen fit.
An example coming soon!