Add a few tablespoons of baking soda to a bowl of warm water. Moisten a clean microfiber cloth with the vinegar mixture and wipe the inside of the microwave. Most dirt should slip right away, but if you have persistent stains or cracks that are difficult to access, Jett suggests using a scrubbing tool that doesn't scratch. Now that you have a clean microwave, make sure to keep it that way by cleaning up spills and splashes as soon as they occur.
If you don't clean it soon after heating the food, it hardens and becomes much harder to clean.