Before you even leave the seller:
- Cold start the engine. If if it's warmed up, you might not see some problems
- Check all the tires.
- Check ALL the fluids, including the oil.
- Check ALL the lights, even in daylight. You can get ticketed for even one light burnt out.
- Take it for a short ride.
After you leave the seller, fill up the fuel tank.
Drive slowly for the first few miles and get used to driving this beast. It's going to be quite different from driving your family car, especially turning and stopping.
As you drive home, stay in the right lane. As you go through Louisiana, you may be required to go through the scales. And LA scales are open 24/7! Don't worry, though. You won't be overweight.