I tried the garbage bagging of my kids playroom. Didn't work. They are extremely strong willed.
Throw thwe stuff out then. One way or the other the clutter is gone. Leave them with 5 outfits of the most hidious clothes imaginable. Dress them like Poindexter a few weeks and let peer presure work for you.
"Didn't work"
I don't get that at all. Once my kids have nothing to play with or wear they seem to keep their nothingness organized pretty well.
I insisted that the carpet in all of the house be accessable to the vacuum cleaner. My wife told the kids that everything in their rooms that was not furniture must be picked up every Friday night for Saturdays vacuuming by me.
Anything that was on the floor was tossed into a garbage bag by me and I would put it in the outside garbage pail then dump the kitchen trash on top of it.
It only took two or three times before they decided Dad wasn't fooling when he said pick it up. The toys were put in the toy boxes, the shoes were put in the shoe racks, clothes were either hung up or put in the laundry baskets.
They did appreciate my rules when they became old enough to do the vacuuming.