Once again it is time to tackle an organizing question for "Ask the Organizer".
"Do you have any suggestions on how to keep books organized -so they are not all over the place?"
To help answer this question I decided to tackle the task in my own home as well.
My two boys share a room and I keep most of the books on a shelf in their room. The shelf was full and needed a little organizing so I took all of the books off and sorted them out. First, I set aside the books that were torn beyond repair. Some were board books from when my oldest was a baby. Then I made a pile to be donated. These were books that never quite made the cut and got pretty lonely. It is time to pass them on to someone that will enjoy them.
I then tried to group them by categories such as general stories, dinosaurs, bible stories, Dr. Seuss, Curious George, etc.

Any board books that could be salvaged were collected and put in a box to go in my daughter's room. 
I also took out any books that belonged to my oldest son such as readers and chapter books and moved them to a higher shelf in the playroom. He loves having a special shelf that the other two cannot reach. 
This is an after shot of the shelf in the boy's room. It was completely full when I started. Now there is room for growth.

We always had books migrating downstairs so I gave them a cabinet of their own which was in need of a little help as well. I sorted, purged and relocated what was necessary and this it what it looks like now...

Often my kids like pulling all of the books out and looking through them but putting them away is their least favorite thing to do, of course! By keeping the selection to a manageable size I notice it becomes a lot less overwhelming for the little ones to put them away.
Another option for keeping book clutter at bay is to store half of the books away and when the kids are ready for something new simply rotate the selection and it will be like taking a trip to the bookstore in their own home.
If your children cannot yet read the spines of the books sort them by categories and store them in baskets on a bookshelf. Your child can take out a basket and flip through the books to see which one he wants or just sit with that "category" of interest until he is ready to put them away.
Keep it simple but still provide an area where they can explore books and start a love of reading.
As always, If you have an organizing question feel free to email me or leave a comment.