storing sweaters

Hi everyone! I have many sweaters I wear year 'round. I especially like cardigans. My problem is, once my sweater has been laundered, I can't seem to store it without ruining it, or at least having to iron it before wearing again. If I fold them with meticulous neatness, and put them in the drawer, when I pull them out, they're all wrinkly. If I hang them on the hanger, they get strechy bumps at the shoulder. What do you do?

Thanks!
Harper