You are effectively hiring your boss.

You want the best boss you could ever dream of. It's your company, so you can do what you want. Furthermore, you hired your people, so if you get along with him/her, so should your people (in theory off course).

Obviously you want someone that understands your proposition, knows the US market and I would say Europe. The more they know, the faster they can get you there.

Last but not least, you want someone commercial and not just a sales person.

I hope this helps, good luck.