Choose a refrigerator with an external ice & water dispenser, to greatly reduce opening the fridge to retrieve those items.
Purchase a Bottom Mount or French Door refrigerator as these models use, on average, 16% less energy than side by side models (according the consumer energy center).
Choose a refrigerator that has a manual defrost, as they use half the energy of an automatic defrost model. This does come with a tradeoff, as the manual unit will need regular servicing.
Make sure your refrigerator is sealed tight, if air is escaping the compressor is working harder than it needs to. Look for units that have a door open/temperature alarm as a feature, they will audibly alert you if something is wrong.
Look for the ENERGY STAR  label on your appliance, as it guarantees it falls within energy efficient guidelines