Date your co-founders

It is best to look at co-founder finding dilemma as a much longer-term process, than, say, just hiring an employee. As you wouldn't propose marriage on a first date, you shouldn't also push to get someone to become a co-founder. Therefore it is better to look into your network first (and yes friends are a great source of co-founders), start with a small engagement, like mini-project, and utilize online startup communities where you can build rapport over time.