Place your plates in an oven preheated to 60°C to 90°C (140° to 194°F) for about 15 minutes. Caution: At temperatures above 80°C (176°F), you risk burning yourself if you touch the plates with your fingers when removing them from the oven.
2:
In the microwave
Place your plates in the microwave for 2 minutes on high, with a cup or glass of water on top (never run a microwave without something containing water, as this could damage it).
3:
With hot water
Place your plates in the sink and run water over them—as hot as possible. Let them soak for 5 minutes, then dry them and use them.
4:
In the dishwasher
Some dishwashers offer a short "Hot Plates" cycle or something similar; just load your plates and start the cycle. But for a more economical option, you can also take advantage of the end of a normal wash cycle, when the plates are still very hot.
Remarks
If you're in a hurry, use the microwave, but if you have a little time, use the oven, where the plates can sit quietly once they're warm, waiting to be used. You can also find electric plate warmers in stores, but they’re not very useful when your oven or microwave can do the same job.