I have a pretty extensive camping list that I have made up over the years.  I keep it on my computer where it is easy to alter/add stuff and print it out.  I have 7 headings.  Food, Bath, Kitchen, Entertainment, Clothes and even one for the Dog.  The longest column is Misc.
Not everything is taken on each trip so it is simply crossed off as if I had loaded it.  This is why the cupboards in my small TC are not near full!!  I do take more food, water and prescription meds than anticipated cause you just never know.
When I reach my camping spots there is no running into town for stuff so I can't afford to forget anything.  Being retired I do a lot of camping.