1. Do not turn on microwave with nothing inside. The microwave would get quickly damage and possibly short circuit. Do not put metal, aluminum foil, low grade cling film, glass, candle, or anything that can either melt or be set on fire in the microwave.
2. Do not microwave a sealed product. The water expands into steam and would explode the sealed container. Always leave an opening or holes. This includes food with skins or shells, such as potato. Always be careful of the steam.
3. Microwave has difficulty cooking a large item evenly. Higher end microwave comes with a turn table and adjustable setting for the size and weight of the object. However, microwave can only penetrate limited depths, so it cannot fully and safely cook a whole chicken or a large fish. Nor can microwave guarantee the entirety of the food would reach the necessary temperature to kill all the bacteria. Depend on the water distribution of the food, some parts may not cook at al. You have to overcook raw meat in a microwave in order to make it food safe. However, this makes the food dry, rubbery, and unappetizing.
4. Microwave heats by heating the water particles in the food. Dry goods will not heat up properly in a microwave. In order to cook dry food in the microwave, you have to create a steam bag using heat resistant parchment paper and add the appropriate amount of water.