Depending on the show--one day or overnight or several days--I make a list.
One day shows usually just get a bucket full of necessities plus a bucket for water for the horses and a cooler of drinks for humans and our lawn chairs. Oh and a clean shirt for the show person--cause coffee just seems to jump out of the cup.
First I ask myself--What will the horse need to transport? Provide for food and drink--covers if necessary ect.
second--What does the horse need to show? Make up products and hoof products as well as show halter ect.
third--what will I need to be there? Clothes and make up for show and clothes for other times of the day and night. Don't forget things like toothbrush and shampoo ect. Also, I almost always carry a small cooler with drinks and snacks cause I may not care for what is offered at a show. Don't forget the lawn chairs.
If we are going to be more than a couple of days, we will also carry a table to put things on in the tack stall. Easier than bending on the floor and easier to keep my horses from pawing it all to pieces while they are in there. (they will still 'help'me take it off the table when I forget to completely cross tie them
)
Lastly, I will bring lights to hang and fans if it is hot. Don't forget extension cords and extra light bulbs as well as some twine to tie cords up and out of the way with. I take these things to the bigger and longer shows as a rule.
OH--forgot the paperwork. Always carry copy (not original) of registeration papers and Coggins (original is best) and health papers (if required) and any measurement paperwork for the steward.