In addition to many plastic items, you can safely use porcelain wares that are not decorated with gold or silver. When it comes to plastics and glass, make sure they are microwave safe. Not all plastic and glass items can be safely used in the microwave. As a general rule of thumb, if the utensil heats up before the food does, it's probably not a good idea to use it in the microwave; but first check the product's instructions.
If you use plastic wrap over the food, don't allow it to come in contact with the food. Instead, we recommend that you use the splatter cover, which will help retain moisture while it does its job of venting the heat produced in the food by the microwaves. And most microwave ovens are not made to be used with metal foil, metal wares, or plates with metallic designs in gold or silver.
Consult your microwave oven instruction guide for what utensils are safe to use. Also, cooking times vary from one type microwave oven to the next, due to differences in power. Your microwave oven manual will provide you with a guide. When in doubt, cook for less time, check the food for doneness, and cook longer if you have to.
USDA Food Guide for Cooking in the Microwave