Snaggletooth's method is just about spot on, however, when said titfer is in the airing cupboard, the drying process tends to alter the wet-formed shape. One of the best ways to let the beret dry and maintain it's shape in the warm, is to spray milk evenly over it (from a good old squirty bottle) just before you put it in the airing cupboard. Something about the lactose in the cow juice seems to help maintain the shape during drying.
Hope this helps
Jobza
PS Don't go mad, mind, too much of the white stuff will leave white marks on the outside funnily enough!