The best commission model is one that reinforces the behavior and activity that you are asking the sales person to do. So if the goal of your sales person is to simply set up free consults, maybe they get a flat fee for each call they set up or maybe a percentage of the deal if it closes? Or maybe you set goals and if they reach the goal each month, they receive a bonus paid monthly. There a variety of ways to set this up but definitely think about the behaviors and how to reinforce for the specific activity you need from the rep.