Label your batteries and keep track of which ones you used in each match (like on a whiteboard). Ideally you are cycling through all your batteries before reusing them. You could use labels like 1 2 3 or A B C, but I recommend fun names - I suggest names related to your team’s theme (for my team, that would be types of tea) or just fun names, “Does anyone know Frank’s charge? When did we last use Billy? Why isn’t Pauline on the charger?!”
Take lots of pictures: of the robot, of the pit crew, the drive team, the stands, the entire team, etc. Photos are great.
If anyone on your team likes making videos, take lots of video too - wrap up videos for events/seasons are really fun for everyone involved.
On a similar note, record video of your robot during the matches and after each match have the drive team review the video. Required? No. Will see improvements? Yes.
If you have team buttons or stickers, consider bringing some to hand out. It’s a thing.
Debrief with the team after the event (as in a few days later). Talk about what went well and what the team can do to make the next event better. Did you need more snacks? Did you have enough water? Were there robot mishaps that could have been prevented with an item on the checklist?
Not sure if this was mentioned, but make sure everyone is hydrated It’s very easy to forget to drink water in all the commotion - I remember how dehydrated I was at my first event