The most common mistake I've seen (and made) is perfect execution of the wrong thing.

Before you start driving, you should know where you're going and how you're going to get there. Otherwise, you might find yourself in the startup maze, and the team can only survive so many pivots before it runs out of gas.

There's an Aesop's fable in which the sun and the wind argue over whose influence is more powerful, so they test it on a traveler passing by. The wind blows as hard as it can, but the traveler only grips his coat tighter. The sun simply shines, and eventually the traveler takes his coat off on his own.

Startups play the wind all the time. They start from their own goals and desires, instead of thinking from their user's reality. Forget the self, don't expect them to move, and go to where they already are.*

*In all regards to product thinking, from flagship features to funnel, onboarding, and retention, nothing else has been as consistently useful for me.

In Node.js, the event loop is what keeps everything running. Block it and everything hangs, everything downstream just sits there waiting. Teams are the same. The next leg of the relay can't start until the baton is handed off.*

To keep things moving, know when it's your turn on stage, know when it's okay (and best) to rest, know when to help backstage, and when to just get out of the way.

*Weekends work great to help with this, to inject momentum into the team come Monday. I also love prototypes for this (back when writing code was the bottleneck). It would derisk things by pulling the future closer and was great for starting forward momentum.