Water in the food will migrate and form ice crystals on the coldest spot, which forms ice crystals and causes other parts of the food to become dehydrated. If there is fat in the food the dry spots can oxidize, which will alter the flavor and smell.
Keeping your freezer at 0 or below, and keeping it full of frozen items will help keep the temperature constant. If you can't keep it full of food, fill a few milk jugs with water and place them inside to help maintain the temperature. Don't put hot food directly into the freezer-let it cool in the refrigerator first.
Keeping food tightly packaged will reduce the amount of water that migrates to the surface during freezing. For example, if you buy a steak at the store and it's in one of those plastic wrapped foam trays, take it out and wrap it tightly. Or better yet, buy from a real meat counter that wraps the meat in butchers paper.