Microwaves must be very clean to work properly. Microwaves work when short waves generate friction, which generates heat and cause the food to cook.

To clean:
Simply put water in a large bowl and bring it to a boil. Keep the door closed and allow to steam for about 5 minutes, then wipe clean. You can add lemon juice to the water if odors are a problem.

Coverings:
~ Never use aluminum foil
~ Never use Ziploc plastic bags
~ Paper towels are used if you want steam to escape
~ Waxed paper is used if you want to keep steam in

Food Arrangement:
~ Put big items on the edges and smaller items in the middle because the middle is the last to heat up.