What to Wear:
1) Shoes - barefoot in warm weather / dark shoes and socks (boys) or tights (girls) in cool weather
2) Colors - khakis or jeans for boys / no large patterns or stripes / choose a color that enhances the subject
3) Avoid - Short sleeves or shorts for adults / a hairdo that easily falls into the face / clothes that kids hate to wear
 
* Clothing above from "Bestdressed Child"