Double Unanimous (principle: team ownership)
Although many confuse this with the founder’s veto practice, it isn't the same.
It's the inverse.
Not getting a veto is a passive event, getting a unanimous "yes" is an active event. Thus, in order to get an employment offer a candidate must actually not only not get a veto, but also get a double unanimous "yes" vote.
The reason I recommend this is that the motivation for vetoing and the motivation for actively saying "yes" is different.
Giving veto rights is equivalent to giving protective rights to existing employees.
Making them all say "yes" gives them responsibility and ownership over the decision to add a new person to the team. If the person winds up not fitting in or not being competent, then everyone takes responsibility. Thus when mistakes happen, which they will, the entire team takes ownership and the team gets stronger as a result.
Beyond the impacts to the team, there is a dramatic impact on the candidate. Imagine what it feels like for them. They interview for a week, to get to TBYB and then have to work for a month to get employment. At first blush it looks like a great way to not get people applying to work for you, but the effect is actually the opposite. If you were an A-level player and you knew the process involved in joining was this difficult, then you would have a high degree of confidence that the people who made it through this process were rockstars and thus you would want to work with them. If you ask most rockstar engineers what they worry about most when joining a company, the answer is consistent, they want to work with other rockstars on really interesting projects. B-Level engineers generally have the exact opposite reaction - complaining about how difficult the interview process is. They generally shy away from companies with strict hiring policies. Let them - you will benefit more. Now imagine what C-level people think of it.
Finally, imagine what it feels like once a person makes it through TBYB and gets an offer for employment. Double Unanimous is a right of passage and every person that gets an offer to become an employee is aware what got them there. For any person that makes it to this point, it creates an incredible sense of empowerment and affirmation that they are the best in their class.
The last effect that it has is that it changes the dynamic between you and the candidate when it comes to the all important founder/candidate meeting. In short it makes your job much easier.
They are on top of the world because they just made it through their right of passage and passed. It is and should be one of the highlights of their career to have made it. So who is going to say no to an employment offer at that point?
The end result is that the acceptance rate to employment offers is incredibly high when using this technique. It makes your budgeting and HR spreadsheets much more predictable, thus making you look good, but more importantly it makes you look like a brilliant rockstar cult leader. The truth is that by installing this process, you ensure victory. It reduces the dependency of the cult of your individual founder cult of personality and utilizes the power of your team - the real cult of personality.