I have a 3 year old and a 4 year old boys. If they do not help clean up when requested, they go to time out. I don't make them clean up the whole thing. I help out a little to get them started and remind them to keep picking up until everything is put away. When there are like 100 pieces, I don't expect their attention span to stick that long. I help out a little (maybe I should be more strict?). If they don't help put away the toy, the next day it's not available to play with.
As they get older, like 6 years old, they can deduct where toys go and why they are taken away. I plan on putting toys left out into a large box or barrell. If I have to pick it up, then it's going "away". Anything left in the box or barrell is getting sold. Either way, I don't plan on putting away all their shoes, clothes, toys, etc for the rest of their lives. So... if they want to know where it's at then they better put it away for themselves. It works great for teenagers and husbands too! My girlfriend uses this method and it gives her piece of mind to know she hasn't coddled the situation by doing their chores and it's off her floor.