Here are some useful tips for maintaining your household appliances.
Washing Machine

Leveling
Because your washing machine is so heavy, when it's not level, it can vibrate strongly during the spin cycle. If your washing machine is not perfectly level (with all four legs touching the floor) it can bang and rock back and forth, and even begin to "walk" across the room. This isn't good for the machine and may damage anything near the machine.
Your washing machine usually has adjustable, front leveling legs with a lock nut. You adjust the leg to the proper height, then tighten the lock nut up against the body of the machine to keep the leg from rotating.
Some machines have adjustable leveling legs in the rear also, and you can adjust them in the same way. Keep the machine as close to the floor as possible, the lower it is, the less likely it is to vibrate.
Dryer

Lint filter
Check and clean the lint filter after every drying cycle. If the lint filter has any rips or tears, replace it. If the filter gets clogged by fabric softener residue or any other residue, you can easily clean it with a soft-bristle brush and a little detergent.
You can also clean the chute, duct, or area that the lint filter fits into. If necessary, use a vacuum cleaner to reach into the duct and clean out any lint.
Stove

Cooktop
You can clean any porcelain cooktop with a non-abrasive cleanser. Don't pour the cleanser directly onto the cooktop, instead, put some cleaner on a soft, damp rag, then wipe the surface.
Refrigerator

Self-defrosting refrigerator
You don't need to manually defrost your self-defrosting refrigerator/freezer. Every 6 to 8 hours, it heats up its cooling coils slightly and melts any frost accumulation on the coils. The resulting water drains into a shallow pan at the bottom of the refrigerator/freezer.
There's no need to empty the pan. The water in it will evaporate. But it may begin to smell bad over time. You may be able to remove it for periodic cleaning by detaching the lower grill and sliding the pan out the front of the refrigerator/freezer.
Note: When mold grows in the drain pan, it is sometimes considered to be a health concern. If your drain pan is removable, and if you're sensitive to mold, consider cleaning the drain pan periodically.
Dishwasher

Interior cleaning & deodorizing
You don't need to clean the interior of your dishwasher if you use it regularly. If it goes un-used for a week or more and begins to develop mold or smell bad, you can clean it using Dishwasher Cleaner and Deodorizer.
Microwave

Interior cleaning
Clean the inside of your microwave frequently. Food particles and splatters absorb some of the microwave energy while the unit is operating and may cause burns and other damage to the microwave. You can clean the interior with a microwave oven cleaner.
Exterior cleaning
The touch pad controls, door hardware, and other exterior trim pieces last longer when they're clean.
Surge protection
Because microwave ovens have solid state circuitry inside, they're susceptible to damage from voltage spikes caused by lightening, etc. It is recommended that you plug your microwave into an appropriate surge suppressor to protect the circuitry.
Door safety
Your microwave oven's door keeps the microwave energy inside, where it belongs. If the door is in any way damaged, or if the door seal doesn't seem to fit correctly or be in good repair, have the microwave checked by a qualified appliance repair technician.
Running empty
Warning! Never operate a microwave oven without food or liquid inside it.
Microwave ovens heat by bombarding the food or liquid in the oven with super-high-frequency microwave sound energy. If there's no food or liquid in the oven to absorb the microwave energy, the energy can feed back to the microwave itself, which can permanently damage the internal microwave antenna (magnetron).