the main thing to get a good mpg is to keep up the maintenance on it. keep the tires at the right psi, change plugs, oil etc...
I hardly every baby mine with a light foot cause I love to hear the exhaust.
and I still get around 20 doing that.
I replace all my fluids with synthetic. thats all I run now. I bet I could get 22+ if I babied it and never stomped on it. but thats not gonna happen. if I get 18+ im happy. my truck has 205,000kms and sill goin strong.