I have mainly flown 172s and 152s but the shutdown/parking checklist was generally something like:
mixture to the idle cut-off position.
fuel selector valve to the "off" position
turn off the master switch
turn off and remove key
A random google turned up this 172 POH in pdf format:
http://www.redskyventures.org/doc/ce...o7-scanned.pdf
It has no standard shutdown checklist but the shutdown due to engine fire in flight emergency procedure starts with mixture to idle cutoff.
The "securing aircraft" checklist does mention electrical first but by that stage the engine has been shutdown.