Shoot Appleseed 25 (meter or yard) with a .22LR, at least for your first one. It is about running a rifle. You will shoot a lot. Save your ammunition money and shoot .22LR, even if you have to borrow or buy one to use.
Have a sling. Have a mat, or a nice piece of thick pile carpet. Try out some elbow pads - you may or may not like them.
Have sights you can see, that have at least a basic zero, and preferably sights you know how to adjust. This will save time and aggravation. I’ll do it with scopes or irons, but they will be sights I know I can see and know how to adjust.
Check your ammo with the gun and magazines you will use. Have more than enough of all the same kind, if possible. If you only bring barely enough, you may have to scrimp on your reps. Bring enough that you can plan to bring a bunch home, then you won’t run out and if someone else has crap ammo, you can help out.
Clean your gun before you get there. You’re going to shoot all day. Starting with a dirty gun is not ideal.
Have enough magazines: you can probably shoot the whole thing and do most activities with two, but you will be reloading quickly and constantly with only two. Having ten is probably overdoing it, but would really make the day simpler, with some safety margin for a failed magazine. Four is a minimum to my mind - I think I had six on my last one, and my daughter with my ancient 10/22 had about eight.
If you only have access to a .22LR with a tube magazine, it can be done, just as it can be done with a bolt action (I got a Rifleman patch with a bolt action) but it is really designed for a semi-auto using detachable box magazines. If you are buying a .22LR to shoot this with, get a semi-auto with detachable box magazines.
IOW, get a basic 10/22 and a handful of 10 round rotary magazines, a nylon military sling, a receiver peep or 4x fixed or no bigger than a 3x9 adjustable scope, a couple of bricks of reasonable quality ammunition (CCI Blazer or SV is fine, doesn’t have to be Eley 10x or Midas or whatever), and have fun.
Bring plenty water and Gatorade and snacks, and a good lunch. If its hot, bring an ice chest with lots of real ice and blue ice.