This is my process. The whole process takes months and as new details come to me, I jot them down on paper. Each character has their own section in my character log book.
When I feel that the characters are whole and real, I start imagining what their adventures will be. I start to make a mini movie in my head as I visualize the 'where and what' of the plotting. The plotting is still work, but plotting seems to come so natural once the characters are fully formed.
When you're writing children stories, you don't have a lot of space to 'tell' about the character's descriptions, nor do you want to. So a lot of the characteristics will come out as other characters meet them or through what that character is doing and saying.
The really cool thing about getting your characters to be real and whole (even if a lot of that information isn't told to the reader), is that it does come out in the story. It comes out in the "Show Don't Tell" that all writers have heard a thousand times. I think it becomes a sub-conscious process to the writer because the writer knows those characters just as much as knowing a long-time friend. And if your characters are real to you, the writer, it is amazing how the illustrator will have the same vision as you had for those characters.
When book one, Sir Princess Petra, was in the illustration stage, I nervously waited and wondered what the artist's vision of the main character, Petra Longstride, would be. I worried for all the characters. After all, I felt my reputation and all my hard work as the writer was at stake.
The thing about the whole creative process is this: if you, the writers, have made believable and whole characters, the illustrator gets it just as easily as if you had sent her photograghs.
When I received the illustrations for book one, they were perfect. All the characters were exactly as I had envisioned them. I had learned about this process in writing school, but until I had been through this process, I wasn't sure that it actually worked. It does work. And when it did work, I knew I had done my job as the writer to create fully rounded, believable characters.
This is exactly what Petra Longstride looked like to me, in my imagination, before the illustrations had even begun. The illustrator of the book is, Samantha Kickingbird and she was assigned by the publisher to my book.
copyright, Diane Mae Robinson, 2012
More on characters in the post "Where Do Characters Come From" here: http://kid-lit-reviews.com/2012/07/04/where-do-characters-come-from/.