Venture Hacks has a good article on how to pick a co-founder. As you may see in another post, the best co-founder in my opinion is nobody. But if you do absolutely need a co-founder, go check out the entry, a few tips from which I’ve included here:
Three co-founders is too many
Think of Wozniak & Jobs, Gates and Allen, Page and Brin. Quick, now think of a trio…..See?
One person builds, one person sells
Don’t step on each other’s toes. And if you both do the same thing, do you need each other?
Don’t use the wrong shorthand to judge your tech or business partner
Titles or degrees don’t mean diddly in the start-up world. Have another tech person (or people) evaluate the coder, and likewise have some razor sharp business folks assess the business person.
Don’t settle
Sure, the process of finding your co-founder will be over, but you’ll regret it more with each passing day.
And perhaps their best tip:
Don’t hesitate to get someone who’s already committed to work on something else part time
Once yours takes off, they’ll drop the other one.
Article: http://venturehacks.com/articles/pick-cofounder