Everyone should "belong" to the group by dressing in similar tones.
Comfortable clothing is key. Stay away from itchy or tight outfits and avoid short dresses for girls. Plan to bring any special toys, hats or blankets. They can make a portrait really memorable. Finally, leave the old tennis shoes at home and wear sandals or even better.... show up in bare feet!
Infants should be dressed in very simple garments. Solid clothing in pastel colors work well.