Spills, if left untreated for some time, can take on a crustiness of their own that can prove both disgusting and difficult to clean. Constantly monitor your fridge for spills. Clean all spills with a wet sponge or cloth as soon as they happen. Before placing anything into your fridge, wipe the rim and or the top of it to ensure that it will not create a spill down the line. Prevention always triumphs cure.
If something that may spill goes into the fridge, try storing it on top of a plate so that it leaks onto the plate.
You should also make a daily habit of inspecting all food items in your fridge for spoilage and what, we at my house like to call, "past-its-primeness". Dispose off these food items before your fridge has a chance to take on new and unwelcome scents.
Once a week, you should wet a sponge or dishcloth with warm water and dish soap and thoroughly wipe down the fridge's doors. This includes the surface area of the fridge's door as well as the nooks and crannies at the top and bottom of the door. The handle is also susceptible to being dirty due to it's frequent use.
Doors have rubber seals around them that should also be cleaned regularly. Be sure to dry everything with a dry clean cloth.
Every season, you should empty out your fridge. This provides a great opportunity to dispose off all items that can no longer be used. Before cleaning out the fridge, turn off the power to the fridge by flipping the switch in your fuse box. The fuse box can be found in the basement (usually) and the fridge breaker should be indicated in writing.
Take out all sections of the fridge as well as all the items inside them.
Allow all parts of the fridge to get to room temperature (including the drawers and crisper that you have removed). Using a combination of 4 cups hot water and 2 tablespoons baking soda, spray and wipe the interior of the fridge as well as all the removed compartments. Allow the solution to sit on the residue before scrubbing and wiping with a sponge and/or cloth.
Repeat the spraying and wiping as required.
Dry and Return
If possible allow compartments to air dry in direct sunlight, or wipe down with a clean dry cloth. Wipe down the interior of the fridge until dry with a clean dry towel as well. Turn on the fridge (fuse box) and begin to refill it with all the food items you took out.
Place an open box of baking soda in the back part of the fridge or a side drawer. This goes a long way in helping control and absorb smells.
Changing the soda once a month will ensure freshness.