I always love to hear about high-mileage Civics. Gives me hope for a few hundred thousand more miles on mine.
Definitely do a standard tune up. It's easy and relatively cheap. Keep your foot out of the gas, and keep your tires inflated.
There is a fuel computer available that gives you instant feedback on our mpgs... that alone could net you the biggest fuel savings, barring any mechanical issues. It's called the
mpguino.
This site is the closest thing to a VX owner's club that you'll find. Definitely read up and ask any questions if you think your car is doing something weird. Chances are, someone here knows how to read the tea leaves.