I used to have a full page checklist for my TT. When I got my class C, I decided I wanted something simpler. CampingWorld has RVMinders that are inexpensive and wrap around the steering wheel.
They have pre-made ones for windows/doors/vents, ladders/steps, slideouts, hookups, etc. I use the ones applicable for my RV and then stuck stickers on the unused ones (there are also 2 blanks) for other things I care about, such as Propane On.
When I arrive at a site, I set up and then slap the RVMinders onto the steering wheel. When I leave, I check the RVMinders on my steering wheel and remove each one as I verify the item (e.g., as soon as I unhook the hookups, I remove the Hookups RVMinder).
Knock on wood, I haven't missed anything since I started using these.