To be a better driver, you have to actually think about driving. No, not while sitting at the computer, while you're driving.
What do I mean by thinking about driving? I mean focusing on it, actually thinking about the act of driving. Most people focus on other stuff - where they're going, what they need to do at work, talking with their friend in the passenger seat, singing along with the radio, the grocery list, whatever. However, you can't possibly do a good job of driving if you're focusing on something else.
Part of driving is accepting and analyzing a constant stream of information and making the right decision every time a decision has to be made. And especially when you're driving on the freeway, that information has to be updated literally every second in order to make the right decisions. That requires a lot of focus. At freeway speeds, three-second-old information is ancient. At 70 mph, three seconds is a little over 300 feet, and you can do a lot of damage in the space of 300 feet.
Focusing on anything else while you're driving increases the chance you'll make a bad decision at some point during your drive. To demonstrate, try this little exercise: sing the first verse of your favorite song. Now put another song on your player, and sing that verse again. Much harder, isn't it? It's more difficult, even much more difficult, to sing that verse, isn't it? That's because something else is vying for your attention - you can't focus on the task at hand nearly as well.
I may be a bit obsessive, but sometimes, especially if traffic is heavy, I keep up a running patter in my head about the traffic around me. It helps me to focus, and helps keep me out of trouble.
And that's another way to be a better driver.