Some method of choosing whose turn it is or the composition of teams. I like to mix up teams between every game and I usually do this by putting all the player names in a bag and choosing at random. There are a ton of phone apps that will chose a player or randomly assign players to teams. I prefer oldschool, but you'll need something, whatever it is.
A LOT of the games are going to use paper, but where possible this should be scrap paper that has already been used for something else. Usually all is needed is one clear side, so scrap printed sheets are usually sufficient.
I do this quite a bit so I have a bunch of blank sheets that I laminated years ago and I reuse over and over again for a number of the games. If you have a laminator, or access to one, and you are going to embark on these games multiple times, it's a bit of a game changer. Also, extremely useful for making a reusable score sheet.
Yes, this will probably be your phone, but if you want to get a stopwatch and hang it around your neck, no one would blame you.
No, I'm not suggesting you go out and buy one of these, in many cases paper or a pad of paper will work fine. But if you had kids at some point then chances are you own one of these and forgot about it. If you do have one...super useful.
From drawing start and finish lines, targets, grids or just labelling things. This stuff is super useful and comes off without any fuss.
You can use these for deciding who is on which team, which team goes first, designating player order. Or any number of other things
I don't know where I'd be without string. Where would any of us be?