how can I get better gas mileage?

Smaller rims and tires high grade plugs cap roter wires air filter injectors oil coolant ect. Might be best to trade it in for a car, you could also put a turbo on it that will get you a little more mpg but really only 2-3 mpg more so it's not worth it really to maintain that level of care for a vehicle that size

You won't ever do too much better, but the other posters have some points. You should get a bit better than that.

On the highway, my Dodge RAM 4WD does +/- 18 to 20 MPG (Imperial gallon) depending on road conditions and sticking about 50 to 55 MPH and a light foot. If I drive faster or put a load or a horse trailer in the back, those figures are out the window. Same goes for urban driving.

Are you hauling all your "stuff" around ? Lighten up.

Have you changed your air filter recently ? Maybe do a tune-up. Incorrect wheel alignment and dragging brakes will increase your fuel consumption too.

Tire pressure should not be at max, but it should be up there, just below max, unless you have a heavy load. High tire pressure will increase rate of tire wear. Check your tire pressure with the tires hot.

You don't say how much mileage is on the engine, but it sounds like you do some maintenance.

Edit:

And yes, smaller diameter tires will reduce your fuel consumption. If you need tires, look for something with a smaller diameter. You can change the rims too, 15" to 14", for example, but that costs more. The tire guys can help you with that when you need tires.

Heavens knows I repeat this often enough. Cars have proper names. You drive a Ford Explorer. Please capitalize the make AND the model names. PLEASE. Broadcast this to all you know in every media you are aware of . Ford Explorer is not a vehicle known for its fuel efficiency when NEW let alone at 20 years of service and about 230,000 miles on the odometer. There is virtually NOTHING you nor anyone can do .I fail to understand the love of trucks by young teens. These are specialized vehicles in truck frames, primitive suspension, incredibly bad fuel delivery to the pistons and bad overall fuel performance due to weight, gearing and just bad design. Since you "love old trucks" you have to put up with the ultra expense of paying $3.50 for each 10 miles traveled.

there are some things you can do but don,t hold your breath on getting too many extra miles on gas ! are the tires inflated at the right amount of air ? is the air filter dirty ? how much stuff you are hauling around ? is it 4 wheel drive ? if it is then your not going to get a lot of gas mileage ! i had a 96 ford f-150 once and i changed the wheel hubs to lock-in and lock-out hubs and it helped some !

Stomping the gas peddle to race to the next stop light wont help matters much. pretend there's an egg between your foot and gas peddle, observe traffic in front of you and coast when ever possible, this is the biggest step in saving fuel there is, Driving Habits.

you can forget about good MPGs with that kind of car and age. even if you did a complete overhaul of that car your not going to get any better then 15-18 MPG. cars from that time frame wasn't really big on fuel efficiency.