I usually only use one head of garlic at a time.
Break apart the garlic into cloves. If you garlic is very fresh, you may want to quickly chop off the bottoms of each clove just to help the process along.
If your garlic was properly dried and stored though you will not need to. Put the garlic in one bowl and place the other bowl on top upside down. Its easier if the bottom bowl is bigger than the top.
Shake the dickens out of it for 30 seconds to a minute and...
Viola! Peeled garlic!