Ram 2500 v10
A big heavy truck with a thirsty V10 ill get you anywhere about 10mpg no matter how you drive it. But these trucks aren't set up for MPG, but for working. Keep it in good running order and tires properly inflated is the best you can do beside trading it in on a Toyota Prius.
If you are worried about fuel costs- you should get something else- your question is funny- a V10 at that! but to maximize the economy of any vehicle, inflate the tires to maximum, go easy on the gas pedal, and lose some weight- throw out anything you carry around on a regular basis- the spare, the jack, the back seat, anything in the bed- etc. etc.
V10 will never get good fuel mileage. Do as the others suggested...properly inflate the tires, drive with a light foot, remove excessive weight from vehicle, run the proper lubricants and make sure the air filter is clean.