Jack up your car
There's a good way and a bad way to jack up your car. Putting a jack under your oil pan, for example, is an excellent way to transfer all of the oil from your engine to the floor of your garage before you replace, well, your oil pan. There are several areas where it's best to put a jack, but if you're unsure, consult your owner's manual. It'll tell you the best spot for your specific car.
Change a tire
The simple fact is that run-flat tires are making the very existence of spare tires more and more rare in today's world. That's no excuse to not know how to jack up your car and change a tire, like the guy in that awful "Handy Man" commercial.
Torque your lug nuts
There are a few points here. First, don't just cinch your lug nuts as tightly as you can get 'em or you'll want to go back in time and kick yourself for doing so as soon as you need to get them off. Use a torque wrench to get them to your manufacturer's specified range -- no more, no less. If you don't have a torque wrench, get one, then use it to torque every other lug nut in a star-shaped pattern (diagonally across from each other) until you've done them all.