When Harvard Business School professor Noam Wasserman studied 10,000 startups for his book The Founder's Dilemmas, he discovered that 65 percent of them failed for the same simple reason: co-founder conflict

That means choosing the right person to start your company with is one of the most consequential decisions you'll make as a founder. And getting it right is obviously hard, a fact startup insiders like Gloria Lin know well. 

The first head of product at Flipboard and the first product manager at Stripe, Lin spent years at mega-successful, fast-growing companies before she decided to found her own startup. All that experience meant she was well aware of how much can go wrong between co-founders. 

That's why she spent a year "dating" six potential co-founders before starting work on a stealth startup with Joel Poloney. She chronicled the whole process in an in-depth First Round Review interview (I discovered the piece as part of their stellar round up of 2019's best advice). 

If you're on the hunt for a co-founder it's well worth a read in full, but perhaps the most useful part of the article is a free PDF offered as an add on. It contains 50 questions, divided into seven buckets representing key aspects of the co-founder partnership, that Lin used to winnow potential co-founders and avoid misunderstandings down the line. 

She explains she dove into this detailed questionnaire only after first ensuring a basic personality and interest match and playing around prototyping ideas for a couple of weeks. If you're at that stage (or hoping to be there soon) you can download the full list, but here's a small taste of some of the more useful and unexpected questions: 

How you operate 

  • What's the worst interpersonal conflict you've dealt with? How did you handle it?

  • How many hours/week are you willing to work? For how long? What sounds good? What sounds like hell?Do you have different expectations for different phases of the company's lifespan? (i.e. willing to work harder in the beginning)

Roles 

  • What would you want your role to be before we reach product/market fit? What would you want your role to be after we reach product/market fit?

Corporate structure and funding 

  • How much money should we raise? (i.e. "zero" to "as much as we can") In the range of "bootstrapped small business" to "go big or go home", where do you want this startup to go? 

  • What does an ideal company exit look like to you? (i.e. "work on company for 1-2 years and sell for 7 figures" to "work for 10 + years, reach 9 figures in revenue, and IPO") 

Personal motivation 

  • What impact do you want to have? Is your startup objective "getting rich" or "changing the world"? Is control or success more important? (i.e. Are you willing to step aside if the company is more likely to have a financially successful outcome or is it important for the founders to stay in control of the company's destiny?)

  • Is it possible to build a wildly successful company without burning out or damaging other parts of your life (family, health, etc.)?

Commitment and finances 

  • What is the minimum monthly salary you need to survive? To be comfortable? To feel like you've "made it?"

Team culture 

  • Complete the sentence: It would make you proud to hear people describe this company's culture as _________________. (Values are written words, and your culture is how you actually live those written words.)

Co-founder relationship 

  • In every partnership, there are times when a partner might breed resentment if certain dissatisfactions don't change over time. How would you deal with a situation like this?