Help your kids to clean up their mess

I want my kids to tidy up their stuff. But how do they know where to put things? I decided to help them with signs I made myself. I pin them onto boxes, doors, wardrobes etc. Those signs are easy to make and removable: 

For my girls' wardrobe I printed out their portraits and some pictures of trousers, dresses, socks and t-shirts (I found them easily on google). I laminated the pictures (you could also just strengthen them with cardboard) and applied them with Velcro dots.

This is what the girls' wardobe looks like: