What's the skill set? Bringing on a co-founder for a specific skill set at an early stage is generally a bad idea because everyone will (and should) be doing ev

What's the skill set? Bringing on a co-founder for a specific skill set at an early stage is generally a bad idea because everyone will (and should) be doing everything for the first few months. If you're pre-product and pre-revenue you should be looking for partners...that is, people who have complementary skill sets and are willing to do everything possible to ensure that the company succeeds. At this stage companies should be split equally among the founders. If you're at a later stage then the percentage should be decided in a brief (emphasis on brief) negotiation process that accounts for existing product value created. In this case, a good rule of thumb is probably 1/n^2 where n=employee number.