If we are talking about the plain regular Levi's 501s, then you should use one of the "dry on you" methods. The reason they feel so stiff is that you let them drip dry or whatever. You need to move around in them while they're a little damp. Personally, I bought 517s (though not shrink-to-fit, IIRC) a short while back, and I wore them straight from the store for a while and then put them in the wash and the dryer inside-out. I don't suggest drying them all the way in the dryer, because they always seem to develop random vertical creases in the legs when I do that. I took them out of the dryer still a little damp and steam ironed them flat, then wore them. You'll need to wear and wash them a LOT before they really break in. I've worn mine probably 30 times since I bought them and they are still pretty stiff, but I like them that way.