Tire Rotation

I remember being very confused as a kid when I heard adults mention getting their tired rotated. It seemed to me that the very act of driving to the place to get them rotated would rotate them plenty. You could drive down the driveway and back and rotate them. I'm not entirely sure when I figured out that rotating your tires refers to switching around their position on the car to even out tire wear. I know I didn't ask any one, I was way too awkward for that. I just bumbled along in my confusion wondering if I was really confused or all adults were idiots. I was a weird kid. Or maybe all kids are weird which makes me normal, I'm still too awkward to ask.
As I talked about in my tire pressure post, you should be checking your tire pressures. When you're doing that, you should be checking your tire wear as well. You're checking to make sure that your tires are wearing evenly across the tread, as well as from tire to tire. One tire wearing weird can be a sign of a problem, that's something you should look into. What happens more often is that your front tires will wear differently than your rears. On my wife's old Audi, the rear tires would always wear before the fronts due to suspension design. On my old Ford Focus the outside of the fronts would wear first because my wife too corners quite quickly. On my truck the front inside edge wears first, again, just because of suspension design. Ideally you should replace all four tires on your vechicle at once. This way you have identical tread design and stickiness at all four corners so all four wheels behave the same when traction gets low. It really is a safety issue. You'd naturally do this if all four tires wore at the same rate, but since then almost never do, you'd always be replacing two tires that wore out on the heavy wear end of the vechicle, and the other two that were just fine. Nobody does that, they usually just replace the two worn ones, leave the other ones and have mismatched tires.
You can prevent that though by rotating your tires and evening out wear so that the set wears evenly. There are two strategies to timing your rotation. You can either pick a mileage (like 10,000 or every other oil change) and rotate them then, or you can just watch them and when you notice that things are different, then rotate. You generally rotate both fronts straight to both backs or front to back crossing. That is you swap the front left tire with the right rear and the right front tire with the left rear. If you alternate rotation methods, every tire will end up riding on every corner of the car. The rotating itself is very easy, it's just like changing a flat tire four times. In fact, it's one of the great automotive tasks that require no special tools. You can use the jack, the lug wrench, and the spare that come with your car. Pick a front corner, swap the tire for the spare, move to the back, swap the tire you just took off for the one that's on there. Move back to the front and replace the spare with the tire you just took off of the back. Now that I count that out, that's three tire changes for one side, so three for the other, it's actually like changing six flat tires. Well, the good news is that by the time you're done you're really good at changing tires with the factory tools that come with your car. This brings up the point that while you don't need any special tools, if you have a better lug wrench, a floor jack and a couple of jack stands, you can do things a lot faster. Now all you have to do is break the lug nuts free, jack up one corner, put it on a jack stand, remove the wheel, move to the other end of the car, use the jack to swap wheels, put the rear wheel back on the front and lower the whole thing down. It's actually a lot easier and it's what I do when I'm near my tools. I did rotate them the old fashioned way a few summers ago when I was away for the summer and my truck needed it, so I've been there too. In fact, when my kids start driving I think I'm going to make them do it with the tools in the car, maybe a couple of times, just so that I know they really know how to use the tools in their car to change a tire. Nothing like doing it six times in a row to really ensure they know the task.
When you have the wheels off, check your brake pads (if you have disk brakes) to see how they're doing. When the car is off the ground and the wheel is tight, wiggle everything to make sure that you don't have any suspension components that are wearing out. I found a bad upper ball joint on my truck yesterday that I wouldn't have known about until it got much much worse. Just poke around under there and give things a good look see. Familiarize yourself with the shocks and the a-arms and all of the bits and pieces that make up the car that gets you around every day. When you need to get something fixed you'll be familiar with it which is useful whether you fix it yourself or have someone do it for you. Knowledge is power. 
Rotating your tires is one of those manly tasks that you should be doing just because you should be doing it. It's good for your car and it costs you nothing but time. If  you don't know when you had them rotated last, go give them a look see. When you rotate them, write it down, keep track of it so you know when to do it next. Go spend some time with tools and cars, it's a good break from sippy cups and diapers.