First of all child characters are usually underestimated. People act as though children are all the same, like their brains are hollow and void of any personality or thought beyond what they see in three-year-olds. When you're making a child character you shouldn't think about trying to make them act young. Every child has a different maturity level, so what you should be thinking about is their personality and background. It's just like making a regular character except for sometimes it's more fun. A main part of what makes every child is not being imature or annoying. It's making them eager and curious. When you are a child you want to be older, you want to know more, try to make that obvious. Also, children like to play games, if you want to play a child character just like an adult who just sits around talking at the shop wall than you should not play a child character. I honestly do not remember enjoying listening to my parents talk when I was younger, nor did I enjoy talking much myself. I played with my friends. Making a child character takes a lot of imagination. Never just think of them as kids, try to think of them as bright, curious little people, each with their own individuality and an eagerness with the world around them.
That will help a lot, but here's a problem. If you want to make a child character you are going to have to make the most amazing background you can think of. Since in being a child character most often you have to be an orphan you are going to have to make your story extremely complex along with their feelings. A child who has lost or been abandoned by their parents would not act the same as one whose parents are always there for them, put that in mind. Also, the "my parents beat me bla bla bla" was brilliant for Rhiannon, but since then it has been annoyingly overused. If you really can't think of something to make your child's background after, turn to a book. I've gotten billions of great ideas just from reading books.
Another thing that is important is what intention you make the character for. A lot of people make child characters just so they can say things to people and get away with it, or run around playing pranks. Some children do do this yes, but I don't really think it adds anything to illarion. A prank once or twice wont hurt a thing, but creating a character just for the point of playing pranks or making fun of orcs will not do much other than annoy people.
This is not in any way meant to be a complaint to anyone, just a suggestion for people to make some child-chars, and a few tips you don't have to follow.
