I have a few pieces of advice for you:
Hydrate. They will stress this to you enough. All I know is, I've been in Kuwait during the summer before, and when I stepped off the aircraft, the heat and wind were so intense, It felt like I was standing in front of a hair blowdryer on high, and I AM NOT exaggerating. It will suck the water and energy right out of you. If there is a hint of yellow in your urine, you need to drink more water. Force yourself to drink it, even if you don't like water. Whenever I feel sluggish "over here", I know that it's because I have not been drinking enough. It rarely has to do with being bummed out because I am away from home, or that I am just plain tired - two bottles of water later and I spring right up.
Baby wipes. You should be able to buy these from AAFES or your BX/PX/NEX. Not all food you eat will agree with you, so I suggest carrying a small pack in whatever 3-day pack or ruck you carry with you to/from work, and to keep a big tub of them in your tent or living quarters.
If you are issued a weapon, pretend it's your 3rd leg, American Express, or whatever else - don't leave home without it! Not because you can be attacked and need it, but because the bigggest danger comes if you misplace it - you will get in BIG trouble!
Get a hobby. For many, it seems to be the gym. I've been gone for over 45 days and I have lost over 20 pounds already, and I have put on some lean muscle. I am a video game player and movie watcher - couch potato by nature, but over "here" that is a waste of your time! You can really transform yourself.
Bite your tongue, but stand up when you are right. You are going to be around some pissy, stressed-out people, and you may become one yourself. Keep yourself in check, avoid conflict with your fellow and sister service members, and remember that everyone is in the same situation with you.
Tell your family that there are going to be periods of time when you can't call them for LONG periods of time, but that they should not worry about you regardless of what they see or hear on the news. Also, tell them that your communications are sometimes cut or go out randomly, and it's hit and miss. You should also make sure to reassure them that if you have a job where you will be "in the rear with the gear". Also, try not to yell on the phone if you are arguing with people at home. I once saw an Army soldier on the phone with his spouse, and the 12 other people in the morale tent knew how stupid he was because he was yelling at his wife over the phone for 5 minutes about their pet dog! 4 minutes wasted where he could be talking to her, telling her how much he loves and misses her, where he could have used the other minute to ask her to buy a carpet cleaner and training to help the dog's problem. Don't be that guy.
Look forward to something. Don't let that thing be "I'm leaving in X days" - set shorter goals. It can be something simple everyday, or once a week. I usually eat extremely healthy and work out all week, but I have one day a week that is "pig-out day", where instead of being disciplined in my diet, I eat things that I want. That doesn't necessarily mean all junk food, but that I eat normally and don't count calories that day. You have to treat yourself to something.
I can't think of much more. Stay safe, have fun, and make the most of your time!
-DM