The easiest way to adjust your sleep schedule is staging it in increments. Many of your daily habits should be scaled back accordingly.
1. Go to bed an hour earlier each day.
2. Dial back your eating schedule by an hour as well. Try to avoid eating or drinking anything before bed. That food energy will keep you up!
3. Don't nap. It will really mess you up. There are techniques for "power napping" but they're suspect at best.
4. Don't use caffeine crutches! If you use soda, coffee, or tea to get a jump start to your day... stop! It may stall you out for a few weeks depending on how much you drink, but it's the best way to create some sort of predictability in sleep. By the same token, don't try to use alcohol to go to sleep if you're of drinking age.
5. Eat a balanced diet, and keep hydrated. There are some nights when a dry system blows through town, and I wake up in the middle of the night dried out. Keeping up with drinking enough fluids corrects this. Again, try to drink an hour in advance to going to bed though. You don't want to be waking up in the middle of the night to go to the bathroom either!
If you're having trouble going to sleep, there are some techniques to help.
The biggest environmental factors in affecting sleep are light and noise.
1. Keep your room as dark as possible! Back when I used to live in an apartment complex, the outside lighting used to pour through the edges of the curtains. This became really annoying. I eventually took a heavy blanket and temporarily nailed it to the corners around the window. This helped a great deal.
2. Sound. This is a tricky one. Normally one would want total silence, but I know this sometimes unnerves people. First thing's first though, and make sure your electronics are off. I used to leave my computer on a lot for
downloads and such, but if you're really having trouble sleeping I've found that the computer has an almost hypnotic effect in keeping you awake. Not fun. If I need any sort of white noise to go to sleep, I use a fan set on low to medium.
I hope this helps. There are a few other things, but I'd say these are the major points.