Try to locate the refrigerator away from heat- producing appliances such as the stove, and out of direct sunlight. Also avoid heat vents. Make sure the machine is level, and that the area around the grill and any vents is both clean and unblocked. A good cleaning once a year will increase both efficiency and life. Wipe moisture from containers and cover liquids.
Excess humidity makes the compressor run longer.
Let hot dishes cool prior to putting them in the fridge or freezer. Freezers that are at least two-thirds full run more efficiently. If near-empty, reuse and fill plastic milk jugs with water and place inside. Use the right cycle. These use far less water.