Looking for a co-founder

Where do you live? In my city there are special meetups I can find on meetup.com, local startup hubs and co working spaces and even Facebook groups that are specifically focused on finding co founders. Alternatively, spending time where people with your skills hang out - LinkedIn, Twitter, etc - would be another way to find one. That said, this is a big decision. If I were in your shoes I'd try to pick someone I know fairly well/have worked with before.