Now I've completed my first comp, there's a few things I wasn't prepared for or didn't prepare well enough.
When you think you have enough snacks, buy more!
Stretching and mobility super important the week prior, my legs were stuffed after squat warmups as I only did gentle and usual foam roller work. Don't rely on all your usual mobility/warm up equipment to be at the venue, take anything you may use at home like powerbands and tennis balls.
Long pants/jumper or jacket to keep the body warm after warm up while waiting for lifts.
Learn to wrap knees.