I’d add: take spare batteries with you (e. g. CR2032s if your power meter or other sensors need them). My 4iiii power meter “surprised me” at my first race (ever) last year, when it dropped from 72 % to 0 % over night. Fortunately, a team mate had a spare with him.
I also always take a big Anker battery pack with me, which allows me to charge two devices at once, be it a cycling computer or a team mate’s cell phone.
If you have Shimano Di2, make sure you have your (proprietary) charging cable with you.