Many Piper aircraft have a round fuel selector with a little known safety feature that you should check before every flight. See the Piper fuel selector pictured below.
This selector is currently drawing from the right fuel tank. Now we turn it to the left tank. However, what if we were busy flying and we accidentally moved it too far, all the way to the Off position?
Fortunately, Piper thought of this and installed a small stopper that will prevent the switch from moving to Off.
See the grey triangle protruding from the bottom of the switch housing. This makes it impossible to turn the fuel to the Off position without first pushing this stopper down out of the way.
When I preflight a Piper I always check this stopper. I push down on and release to verify that the spring is working to push it back up. Then I verify that I have left it in the up position and wiggle the fuel handle to verify that it is not able to move to Off.
As one extra layer of safety for short flights requiring only one change of the fuel tanks, I will start the switch on the left side. That way my only switch of tanks will be to the right, away from the Off position.
These tiny, seemingly-paranoid steps are a part of my overall goal of breaking accident chains wherever I can.