Yes, the "right foot mod" is the number one way to increase economy.
As Gene mentioned above, a ScanGaugeII is really handy for improving your fuel economy. Not only that, but it is a code reader, trip meter, and tells you all sorts of other things, too.
Use LRR tires, such as the ones VW sold the cars with, and keep them pumped up. I switched to snow tires and it took a good 3-4 MG off.
If you use a roof rack, remove it when it is not needed.
Mostly, though, it is about driving smarter. If you have a lot of hills in your area, it is best (for fuel economy) to gain speed when nearing the bottom of a hill, then let that extra speed bleed off on the uphill portion. Of course, use common sense and drive safely.
A long portion of my daily commute is on a 50 MPH country highway. When traffic is slow, and moving at ~50 MPH, my mileage easily creeps up above 50 MPG. When traffic is moving along at 60 MPH, my mileage creeps down into the high 40s. On a 65-70 MPH stretch, it creeps down to the low 40s. Once I get on slower roads, my average climbs back up. People claim to get really good mileage at high speeds, but without a ScanGauge, you don't see that high speed kills mileage, and slow speeds bring it back up.
Note: My mileage would be better if not for the hills. Most of the roads I am driving on hug the coast and go from near 0' above sea level to 175' above sea level... many times.
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