Install manual locking front hubs. When you're driving, your front wheels are permanently connected to the front axles, differential & driveshaft, which means that your front drivetrain is always being turned by the front wheels whenever you are driving. Manual locking hubs will allow you to disconnect the wheels from the axles when you are driving in normal street conditions, reducing the amount of drag & eliminating the power usage that it takes to overcome that drag.

While I haven't personally done this to my 95 SR yet (it's on the list of things to do), others have & have reported noticeable mileage improvements.

Summit Racing has the Superwinch hubs here:

http://store.summitracing.com/partd...7649+4294925134+115&autoview=sku

Other than what MontyMcV has already posted above regarding maintenance & tire size, you should switch your engine oil & drivetrain fluids to a synthetic oil, which should improve mileage somewhat by reducing friction.