1) Place anything I find in a ziplock from hidden areas and place it on the center console or the dashboard.
2) Check tire pressure, fill to proper psi if needed, and leave a post-it note with the Before and After readings. Also inform them if a) front tires indicate a wheel alignment, b) if the tires are showing wear indicators.
3) Remind them to fuel if their fuel gauge reads 1/4 or below.