5 commandments for choosing a co-founder

No decision is more important in a startup's life than the decision of who to start the company with. The right founding team can quickly find product-market fit, while an imbalanced team can find themselves working two years on a product nobody wants.

"What matters is not ideas, but the people who have them," Y Combinator partner Paul Graham said in 2005. "Good people can fix bad ideas, but good ideas can't save bad people."

I've seen hundreds of startups blow up because of teams that didn't know or respect each other. I've heard of everything from money laundering to sabotage. Starting a company is one of the most stressful things you can do -- you had better make sure that your team can withstand the pressure.

So how do you find the right co-founder? What makes for a great founding team? How do you avoid disaster?

Here are my co-founder commandments for startup success:

1. Know your co-founder before your startup. This is the best way to avoid a startup disaster. Startups founded by friends or colleagues that know each other simply have a better chance of succeeding. If you've built up that trust and respect for each other, you will encounter far less disturbing surprises.
2. Complementary teams float and unbalanced teams capsize. It seems obvious, but you'd be surprised how many startups I encounter that have no technical co-founders. Complementary skill sets makes it easier to divide the workload, while unbalanced teams are typically missing crucial skill sets. Fill any major gaps you have on your team before your ship sinks.
3. Make sure you share the same core values. It's fine if co-founders have drastically different personalities and skill sets, but their values have to be the same as yours. You must agree on vision, direction, recruiting, hiring and other core aspects of the company. Disagreement on core values only helps foster resentment.
4. Trust, but document. Get your agreements on paper, no matter how much you trust your co-founder. I've seen at least a dozen startup founders screw each other over because they weren't on the same page and didn't have paperwork that would have prevented a lawsuit. You may not like lawyers or paperwork, but you need both.
5. Build something together first. There's only one way to know if you work well with somebody, and that's to actually work with them. Build something simple together -- a game or an app -- and you will quickly find out how well you work as a team. Hackathons are a great way to test team cohesion.

There's a reason why my co-founder for The Peep Project is Hilary Karls. We've known each other far longer than our startup, and that has given us the time to build up the respect and trust that is essential to running a successful company.

Having no co-founder makes you susceptible to bad ideas because you have nobody to talk you out of them. Having the wrong co-founders will create stress fractures that eventually tear your startup apart. But having the right co-founders will transform your startup's destiny and propel you forward.

If you want to do a startup someday, go looking for your co-founders now, before you actually need them. Meet interesting people and see who you click with. You'll thank me later.