(Editor’s note: Mike McDerment is the co-founder and CEO of FreshBooks, an online invoicing and bookkeeping app. This story originally appeared on the company’s blog.)

They say choosing your partner is the most important decision you will make in life. I’d say choosing your co-founder(s) is the most important decision you will make in building your company. Here are five tips to help you choose wisely:handshake

Demand Passion – Starting a company is lonely, thankless and costly. It will test the deepest fibers of your being. The only thing that melts these obstacles away, leaves you raring for more, is passion. You can’t fake passion. It lights up your eyes and charges your voice when you talk about what you love. If you have a great idea, and you want to bring it to life, find someone who is passionate about your vision.

Trust – You either have it or you don’t. When the dark clouds come – and they will – you find out really quickly if you trust someone. When your mortgage is on the line, you better have trust. Mistrust is a cancer in relationships; it breeds sleepless nights and suspicion. The good news is you can avoid it by choosing a founder you trust, then work to foster deeper trust in your relationship over time. Keep in mind that it’s a never ending process.

More than Money – There’s more to life than money, and chances are money is a long way off if you are building a company. So again, find someone with passion as they are sure to be in it for more than the money.

Choose your Complement – Like a partner, a co-founder should be strong in areas you are not. A great complement to your skills is someone who loves to do things you hate, someone who makes the sum of your parts greater than the whole.

Give them Equity – This may seem like a no-brainer when founding a company, but I meet people who expect others to care as much as them about the business when they don’t own any of it. If you believe they will if they don’t own a piece of the business you are seriously deluded.

Photo by Andyrob via Flickr