Kids tend to accumulate lots of small toys like race cars and action figures. Try storing the toys in a hanging jewellery holder instead of a box.
Over at Apartment Therapy they have listed tips for trying to keep kids' rooms clean. Your children may forget about toys in boxes, but displaying them in a clear jewellery holder lets them see their entire bounty. Plus, the toys are less likely to end up on floor and stepped on if you keep them above ground.
Check the link for other storage ideas for the kids.
15 Real Life Storage Solutions for Kids Rooms [Apartment Therapy]