What and how you store food in your refrigerator can effect the amount of energy that is consumed. Keeping your refrigerator full actually helps increase energy efficiency because there is less air to cool when space is taken up. Be careful not to overfill though. Overfilling your refrigerator can hinder air circulation in the appliance.
Also, keep liquids covered and make sure to wrap foods when they are stored in the refrigerator. Not only will uncovered foods dry out and ruin the taste, but the moisture that is released causes the refrigerator's compressor to work harder.