I've been sending packages to my nephew in Afghanistan.
First, go to the post office and get a LARGE FLAT RATE PRIORITY BOX. The boxes are free, and you can send any weight amount of stuff that fits in the box for a flat fee (I think it was about $11 or $12), and they also give you $2.00 discount off the 'regular' flat rate price if it is going APO or APE.
Some of the things I put in the box for my nephew: Toothpaste, toothbrush, dental floss, chapstick, q-tips, hand sanitizer, baby wipes, insect repellant with DEET, Sunscreen, dark color socks and t-shirts.
For Fun: I put a yo-yo, a deck of cards, a sketchbook and charcol pencils, a word search book, waterballoons, a nerf ball, a slinky.
Food, always lots of food! Gummy Bears, flavor packs for bottled water, ramen noodles, Lipton cup o soup, tea bags, hot chocolate packs, Kraft Easy Mac, Gum, Lifesavers, Twizzlers, hard candies, marshmallow Peeps, pez dispenser, cookies, granola bars, raisins, trail mix, sunflower seeds, peanuts, beef jerky/slim jims (pork products are Forbidden, so be careful with meat things), peanut butter crackers, tuna fish in the foil packets.
My kids had a ball shopping and picking out things for him. Also be sure to enclose a letter or a card, have the kids draw a picture, include some photos and maybe some articles from the local paper.