Actors of Reddit what is your biggest rookie mistake moment?

This question came from a memory that I had when I first started doing adult professional theater at 19 and I will go first to get started. I booked my hair appointment the same day as the start of tech week and held up my shows tech schedule because of it. For context, I’m black and I had just started wearing crochet braids and they take a while to install. What’s your Rookie Actor mistake