Kids can really get better quickly. Here's another thing I would like to say: Kids should never be coached by their parents, ever. They should be as natural as possible.
I have found that so many directors and producers in the room say nothing, and this can be deadly. It's very difficult to audition for comedy in the vacuum of a small room, but it's the only way most do it.
I would say take any work you can get. Don't pass on something if it's a commercial. Take it. Work really does lead to other work. Especially if you're just starting out, work begets work.
The legwork is always hard. Really finding people that you think are good enough. Just the definition of what we have to do is finding good enough people that you really think are special.
