Your body needs time to store the water, and trying to chug a water bottle right before you leave is ineffective and uncomfortable. Aim to drink one glass of water every hour up until you set out on your run. You need to drink water to stay hydrated and energized. Aim for 8-16oz of water 1-2 hours before running. You don't need to eat a lot unless you plan on running more than 12-13 miles. A bagel with honey or jam, a granola bar and fruit, or a peanut butter and jelly sandwich will provide fuel that your body can digest quickly. Avoid slow to digest foods like thick pasta sauces, fried foods, or cheeses. Aim for a simple combination of carbohydrates (bagel, toast, granola, oatmeal), natural sugar (jelly, banana, apple, honey), and protein (peanut butter, yogurt, grilled chicken). This is especially important if you are just beginning to run regularly. Use a map or a running specific app, like MapMyRun, to plan out a route that works for you. A good start for your first few weeks is 20-30 minutes, running 2-3 miles at a time. As you progress, listen to your body -- if your muscles and joints are hurting after every run, slow down and do less mileage until you are better prepared. You should wear light, breathable clothing that doesn't trap sweat. If you are going for a short run, then a cotton shirt will be fine, but you should use synthetic athletic wear for longer runs. Your body will raise it's temperature by 10-15 degrees, so dress as if the weather is 10-15 degrees warmer. Make sure your sneakers fit by trying them out on short runs. If you get any blisters or feel numbness in your toes, you need better fitting shoes. Your heel should stay snugly in the shoe. You should have room to wiggle your toes. The balls and arches of your feet should be comfortable but not tight. There is a growing movement to run barefoot for it's supposed health benefits, but only try it if you are sure you will not step on anything dangerous.

Summary:
Hydrate throughout the day. Eat a simple meal 2-3 hours before you plan on running. Set a reasonable goal. Dress to exercise. Buy running shoes.