First thing is get yourself a scangauge. Its about $100. That may sound like a lot but you're about to get 50% better than the EPA rated mileage for your car. That scangauge gives you real-time feedback about your driving.
Next thing is fill the tires up to the maximum rated pressure for them.
Now it comes down to driving techniques:
1. Increase the distance between you and the car in front of you by double. You'll see why in a minute.
2. As you encounter traffic try to use your increased distance to coast as long as possible in neutral until you have to stop. This saved me recently. A lady in front of me was texting in traffic and crashed into the person in front of her. I was coasting and able to easily avoid hitting her.
3. Stop lights - coast to the stop light in neutral. When you stop put the car back in drive.
4. Acceleration - accelerate as slow as possible and go no faster than the speed limit. Ideally slower than the limit especially on highways. Fast acceleration kills MPG
5. Highways - if the speed limit is 55 oscillate between 60 throw the car in neutral and coast to 50. Then rinse and repeat. This is especially useful coasting down hills on the highway. Accelerate slowly up the hill and then coast down in neutral as far as possible within reason. Note that you'll need to stay to the right lane because people behind you will go insane.
This is a skill. That's why the scangauge helps you hone your ability. At first I only got the EPA MPG. Then I beat it a little. Now I'm destroying it. Just takes practice. http://www.amazon.com/gp/aw/d/B000AAMY86
Consider this. I drive 320 miles per week. At 26mpg that my old car got that cost me $50 per week. I raised it to 35mpg just by doing this. That saved me $15 a week or $60 per month. Scangauge paid for itself in less than 3 months.
My new car is rated 42mpg. I'm averaging 65mpg going to work. That brings my cost down to $19 a week. :-)
Yes, hubby recently got himself a 2010 Honda Insight. He loves it. I'm not happy with the seats because they're so darn uncomfortable, but as long as hubby is happy, I'm happy. He's happy because now he gets almost 70MPG every day he drives to work. But even if you have sucky MPG rating on your car you can save gas and money by driving more slowly.
PS: someday soon we will be videotaping what happens on Chris's commute and putting it on YouTube. I'm sure it'll be hilarious how insane people get.