I get my best results when driving at a nearly constant speed. View your brakes as something you use only in an emergency, try to anticipate when the lights will change to red to coast into them. I also use cruise control even in town.

This weekend I drove strickly on city streets, for 70 miles and got 43.7 mpg.

The other trick is to keep everything warm. I combine trips to do this. The longer the trip, the better the mileage.