Classy but Comfy. Maybe a dress/dress pants, but then sneakers. This will avoid "posed" pictures.
keep as much natural. let the personality shine through
Pastel's are fun for spring, as long as the look is overall simplistic.
a simple splash of color (which can be taken on/off if necessary) creates a fun atmosphere of color and whimsy.
Layering is good because we can easily alter the look and also is versatile should the weather fluctuate during the shoot. This look is clean and simple, while still sophisticated.
J.Crew - Girls' organdy bow dress
Cotton will be comfortable for kids to shoot in, and neutral color combinations are aesthetically easy to work with.
Comfy and crisp dress like this J.Crew one