Choose a mini fridge by evaluating its size, price, interior configuration, overall design and ability to keep foods cold enough to retard bacteria growth. Although energy efficiency is also a consideration, mini fridges use more energy than their larger counterparts, even when the product is advertised as Energy-Star rated.
Buy as large a mini fridge as your budget allows. Not only does a larger fridge hold more food; larger mini fridges are typically more efficient and offer better performance than smaller ones.
Be very selective about the interior configuration of the mini fridge. For instance, someone intending to store many small items such as cans soda should avoid door shelves that are designed for larger items such as two-litre bottles of soda.
Unless the mini fridge is intended to hold nothing but beverages, avoid thermoelectric coolers. Such coolers may seem desirable because of their light weight and low price, but they typically do a poor job of keeping perishable foods safely cold.
If you do not own your home, consult with the owner to determine if there are any restrictions on using a mini fridge on the premises. This primarily applies to college dorm rooms, some of which may have policies against such appliances.