My niece was like that when she was little. I think it just makes them feel "grown up." And them wanting to do it is just to feel closer to you, because you are doing it. Anyhow, for my niece and my friends little ones I always buy them LipSmackers or some kind of gloss. Nail polish, I would go light colors. Pastels or gloss. I remember when I was little it just seemed so glamorous. Very movie starish.