Without having further details, I have always been a fan of bootstrapping- that is using your own funds and capital to start the business. If your objection to this may be that you don't have access to the kind of funding that is required through your personal savings but bootstrapping can be done through customer validation (pre-sales), business optimization (existing products) and personal capacity building (earn/save more). I hope this is helpful!

Hey there! This doesn't seem to meet the definition of a partnership, especially if all of the funding is coming from you. You certainly want to demonstrate that you value his expertise and contributions but it really sounds like you are bringing your first employee (if you are based in the U.S. learn more about how the IRS designated independent contractors from employees here http://bit.ly/IRScontractorvsemployee). Without having many other details, my suggestion is that you connect with your local economic development council or workforce council to prepare yourself for becoming an employer. Your discussions will change from percentage to salary. You might also consider developing an operating agreement for commission-based compensation on any sales that he brings in.

I really hope this helps!