Ask any high performing software engineering manager how to get the most out of their developers and they will tell you it is simple, give them as many big monitors as they want. The cost of the monitors will be more than returned in less than week from the happy coders, often through out of hours work.

How does this psychology apply to sales people? Well for starters a big monitor is unlikely to cut it, since most top performing sales people are coin operated. This might sound somewhat mercenary, however it has proven to be the case throughout history. 

Having spoken to a number of business leaders it is apparent that the most effective method is to delight your team and find creative ways to provide financial reward. Capping commission and not being transparent or finding ways to keep your team up to date will not help. In the complex businesses that many of us work in, motivating sales reps is surprisingly simple - provide a way for them to share in the spoils and they will reward you with outstanding results. But don't take my word for it, read what a leading Silicon Valley VC has to say on the subject.