We have always had our kids help with chores, even from the youngest of ages. I'm a bit Type A when it comes to clutter and keeping like toys together. My second-born however, is NOT. She likes to mix everything together, every day.
We have finally gotten to the point where we're both happy with the arrangement. Our bedrooms are small, and our second-daughter's room is exceptionally small.
I can't say enough, that kids need to get used to picking up after themselves before they pull out new toys, move onto another activity, and before they go to bed. It's a habit in our house and because of that, I really don't have to say much about clean up.
FIND A PLACE FOR EVERYTHING
This might take some time. It can be a huge job to sort through the massive amount of toys, legos and little pieces your kids accumulate. However, if you start with a place for the toys they play with most - slowly things become sorted on their own. Clear bins REALLY help kids to see where to put things.
MAKE IT EASY TO PICK UP
We use the open bins below for books and specific toys. Our girls know what goes where and it's quick and easy for little hands to clean up with these. They don't have to open lids, and it's easy to see inside.
We also sort little toys with these:
And some of our Barbies stand up in these when they're picked up:
There's also something to be said for a simple zip-top bag. Ours hold the smallest of toys like barbie accessories, very well. We even save the plastic snap bags in which kids chapsticks and nail polish - and even character underwear come! They are more durable and again, are easy for tiny fingers to close.
TOSS THE JUNK
This is a periodic and never-ending job. Take a grocery bag in there every now and then and toss all of those kids' meal toys and ripped paper creations that have no business cluttering up the space. Donate or put on a rotation and pack away things they don't play with. If it's sitting in there and getting no use but you feel bad getting rid of it - part ways. If you don't love something - "release it and let someone else love it." This is said by one of my favorites at flylady.net.
Our play-doh stays high up in the hall closet so only I can reach it when it's time to play. At the moment, Strawberry Shortcake and her cronies are in one of the plastic shoeboxes linked above, in the bedroom closet. They're easy for me to reach when she wants it, but out of the way enough so that it's not all dumped out all of the time.
PICK UP OR SUCK UP
Our 9 year old's room is almost always picked up and our 4 year old is well on her way. But, before I vacuum (and maybe this sounds awful) I call out "pick up or suck up," and that means, whatever is on the floor in the next 10 minutes will be eaten by my yellow Dyson. I haven't had to test the theory. It's all in fun and the kids don't get mad; it just means, go pick up your stuff.
With a little consistency, this stuff works very well. The kids get to play with what they want, when they want and I'm not overwhelmed by the mess!