Start by taking inventory of the room and, if they are old enough, have the children help. Get some boxes and label them for clothes (too small, out of season, keepers) and toys (favorites, too old for, missing pieces/broken) and make a game out of it. Give everyone a box and see who can fill their box up the quickest. Keep going until everything is sorted.

Next you can move on to actually sorting the toys. Go through the missing and broken box first. See if any of the toys are worth saving until you find the missing pieces. If not pitch them. Also decide if the broken toys can be fixed, or not.

Then go through the toys that the child is too old for, and decide together what should be done with them. If there is a younger sibling or cousin, maybe they would like to pass them on to them. If not, see if the child wants to donate the toys in good shape to charity. You'll be surprised at how generous kids can really be if given the opportunity.

Last, go through the favorite toy box. These are the ones that need to find a home either in the bedroom or a playroom (if you have one).

When sorting the favorite toys, determine if you have enough storage in the room for all of them. Plastic storage bins are great for kids' rooms, especially the stackable ones with drawers. Some come with wheels, and can be easily stored in a closet and brought out when the child wants to play. Try to establish a new habit of only getting out one toy at a time, to help keep the room from getting cluttered again.

Finally, it's time to tackle the clothes. With children growing so quickly, it's a good idea to go through their closets and dressers at the beginning of each season. As with the toys, decide together what to do with any clothes that are too small, but still in good shape. Many charities are very glad to receive children's clothing.

Under the bed storage boxes are great for out of season clothing. Then as the weather changes, swap what's in the dresser for what's under the bed. When you swap out the clothes, again check for things they've outgrown. It's also good to have a designated place for the kids to put the clothes that are too small, so when they try something on, they don't just put it back in the drawer.

Once the room has been organized, teach the child to keep up with it on their own, with a routine every day of putting things where they belong.