It's a 2000 jeep cherokee sport and it supposedly gets 16 mpg and I'd like to get that as high as possible. I'm going to remove the roof rack and I'm considering getting full moon hubcaps..will that make a significant difference? And any other suggestions are welcome.
Put your tire pressure up to the rated maximum. If you're willing to drive slow and put in the effort a ScanGauge II might be worth investing in. You could get a lot of the benefit by just studying hypermiling techniques. If you're in a manual, I outlined my driving algorithm. Not definitive, by any means, but it gives one possible way to hypermile.
: a psychological condition or a relationship in which a person is controlled or manipulated by another who is affected with a pathological condition (as an addiction to alcohol or heroin) ; broadly : dependence on the needs of or control by another
Welcome to the site. Hang around, make yourself comfortable, read about what people are doing. As said above, the most gains you'll see are from changing your driving techniques.
Removing the rack will help a little. The hubcaps probably won't pay for themselves, but they could look cool. As mentioned, tire pressure can make a huge difference; you may have to experiment to get it right. The minimum is whatever is posted on the vehicle; the maximum is (usually) what is stamped on the tire's sidewall. If you get up to the maximum and it still rides/handles nicely, that's great (and you'll just have to watch for excessive center wear). If it rides or handles badly, back it off a little.
The first driving technique to practice is planning ahead to avoid using your brakes. Every time you brake, you waste gas that you've previously spent accelerating. So, carry a little more of your speed into and through turns (not too much in a Cherokee) instead of braking more before the turn and accelerating more after. If there's a red light ahead, you should take your foot off the gas pedal; there's no need to maintain your current speed until just before the light and then brake in a short distance. Even better, if you slow down just right (may require brakes) beforehand, you may reach a green light instead of a red light.
There are plenty more techniques, some as obvious as that one, some weird ones, and some that may sound scary. They are listed in various FAQs, introduction to hypermiling posts, and so on. There's strategies that require you to learn your roads, ones that require you to learn your vehicle, and some that require patience. They almost all revolve around paying attention to where the energy goes and trying to keep as much of it as you can.