Welcome to GS!
Get some way to see instant FE -- if the SG-2 is too expensive, get something to show your air/fuel ratio versus how hard you're pressing the gas pedal (seat-of pants maybe) and you have a cheapo version. Otherwise, 99% of us here swear by the ScanGauge. The other 1% owns SUVs, so they left
As mentioned, over-inflate your tires, slow down (keep it under 60 mph if possible), coast as much as possible and...
Ask us any questions you might have.
Good luck, and Happy FE-ing
RH77