The main aspect to remember when using your microwave is to cover your food before you put it in the microwave. If you cover your food with a paper towel then you do not have to worry about splatter when the food gets overheated. This will reduce the amount of time you have to spend scrubbing your microwave to begin with.
Ok so sometimes we all forget to cover our food - and then the food hardens. Ick! The easiest way to remove those stains is to use a microwave safe bowl and put water in it, then heat it for a few minutes and let it sit in the microwave when it is finish heating so the steam helps break up the stains. This will make them easy to wipe away and remove.
Also, a helpful hint for you if your microwave starts to smell is to actually heat up a lemon in your microwave for a minute or two (I know this sounds crazy) but it actually works! Lemons helps disinfect which is what causes odor in the first place!
Hope this helps!