If you're still using your camera on the "green" setting, you don't need a checklist.
The green setting is on the exposure mode knob.
It's the green camera icon or the term Auto in green .
Once you venture into setting the controls on your camera yourself, you need to remember to check them.
For example, let's say last night you were photographing in a living room.
You set the ISO to 1600 and the white balance to tungsten (light bulb icon).
Today, you're about to photograph a fountain in the sun.
When you go to use your camera, you have to remember to reset the ISO and white balance.
Otherwise, you'll be using the wrong settings.
Create a checklist that you keep inside the camera case or bag.
Soon, you won't need it, as you'll remember to check the settings.
Here's an example of a checklist (PDF).