How about dressing the youngster as a song? For her first halloween, We dressed Loren in a little gold lamé outfit lined with fleece for comfort and warmth. I crocheted her a purple toupee out of eyelash yarn. I made a sticker for her that said free the Expo '67 and a gold lamé hat. Several people even got it. She was happy and enjoyed the attention and adventure.
Avoid face paint and anything scratchy or binding is my advice.