it's all in acceleration man. Don't let the RPM's get above 2000 usually. It takes a while, but if you accelerate really slowly, it helps save a ton of gas. Braking also can kill you. You just have to be smart with how fast youre going, like if a light has been green for a while and you think it might turn red, ease up on the gas or cut it and start coasting. If you do it right, you can go through every light at decent speed and never have to accelerate a lot. Also, if you can help it, never stop at red lights, just roll slowly and give yourself space. Also, obeying speed limits helps a lot, even though it sucks. Having the windows down instead of air conditioning below 45 m/h will help too. Above that, drag reduces gas mileage more than the air conditioning does.
These are all really easy ways to increase gas mileage. My dad uses these and increased his gas mileage on his 97 ford explorer with 330,000 miles on it to 22 miles/gallon(when he bought it, the gas mileage was 18/gal).