Organizing kid's toys with supreme focus on style only, becomes a young parent's design quicksand! That that sort of approach works until the child reaches the age of one, and has his or her own "design" idea!
As a former Pre-K teacher, I know that each child has his or her own way of doing things that makes sense to them, and why not? We adults are the same way! SO, with that in mind, here are my suggestions:
Take cues from your child and get creative with furniture!
If Mary likes to "stuff things into baskets randomly, then find a set of baskets that will contain the clutter and try not to stress too much over the chaos in the baskets! Consider it your parental victory if she learns to clean up (in her own way) by depositing her toys in her baskets when she's finished playing! She'll feel good being a helper by keeping her space clean!
Perhaps you have neat Nick! You could use the same basket system but instead of randomly throwing everything into baskets like Mary does, you could help Nick designate a type of item for each basket. I like to use the small round labels (made of card stock with tin edges) made for labeling keys. Assuming Nick can read, you can let him choose what will go into each basket, write the name of that item on the tag (front and back, in case it flips over) and then tie it onto the basket with a ribbon or short piece of rope. Next time Nick makes his room neat, all he has to do is look for the tag with "Hotwheels" on it and drop in those cars!. If Nick is too young to read, a sticker or a picture of the item can be used to label the basket. Be sure to write the name of the toy too! This will help the child to associate the word with the picture and the item; giving him a foundation for future reading!
It you have a clutter Bea and she's happy the way she is, well...you have your hands full! Shelves inside closets and a chest of drawers can help her Bea keep her clutter contained! It's still very important to teach children to take care of what they have but it's equally important to be careful to recognize their efforts and praise them for doing their best (even if it's different then your idea of organization)!
For books and magazines, I'm a big fan of stepped book stands that display books and magazines so they show the cover (rather than the spine), making it easy for your child to find what they are looking for and easy to clean up!
Art and artwork gives creative kid a boost in confidence when they see their art displayed! I love the art easel by Melissa and Doug! There's a place for every art medium and it keeps things within easy reach for your Picasso! When they create a new masterpiece, you can use frames with a hinged front, to change out art. Matting and framing select pieces that you know you will treasure for years, is another way to showcase their creations for both of you to enjoy! If they have made sculptures of clay or any other bulky piece of artwork, a house bracket (corbel) or shelf will keep them in view! Remember: Your small fries are short! Keep the art low so they can see it and display some at adult eye level too, to keep the room from looking too bottom heavy.
I have many posts related to organizing children's items. When you visit The reNOUNed Nest, be sure to use the "Search the Nest" box in the right hand column. Try searching for things like: Nursery, kids, undecorators (my pet name for my kids) and organizing.
Have fun and remember, they're only little for a short time! Enjoy them and love them every chance you get!