Do an extremely thorough inspection of the exterior and interior for flaws. Make sure that every switch operates and every function works. Check air pressure and oil level. If it has any grease fittings give them a few pumps sometime soon after you get it to make sure they have a decent amount of grease in them. GM trucks have very little grease in the steering joints. I actually re-torqued the lug nuts on the new truck but I'm weird. Take as much time as you need at the dealer and have anything documented. My salesman friend says the majority of people never even look under the hood during the buying process.