Here's another tip. Take this pretty much as far as you want. If your car has a built in instantaneous fuel economy display, you can monitor that and drive accordingly. Sometimes, when there's no traffic, I'll try not to let it drop below say, 25 mpg. What that means is, as you go up hill, you actually let off the gas, the opposite of what your instinct wants to do.
This works wonders, believe it or not. My truck has an EPA estimated 15 mpg city and 18 Highway. I've averaged around 23 miles to the gallon. Not too shabby, I wouldn't say.
If your car doesn't have the fuel economy display, you can do what I did, and that's buy a ScanGauge. They're around $150, and no real "hypermiler" would be without one.
You know the stuff works when you come to the day you used to refuel, and you've got like ¼ tank left.