When choosing outfits start with a color pallet and make sure to choose different textures and patterns within that color pallet.
When selecting colors you should consider the background. For example, Pick warm colors when shooting outdoors to compliment the greens and blues of nature. In my studio, I have royal blue, brown, and off-white couches. Everything else is very neutral so most colors work.
For moms: choose an outfit that doesn't require much maintenance. Make sure your undergarments are correct for the outfit so you're not fiddling to much.
Try to avoid neon colors and graphics in most situations. (this could work in a solo portrait situation though)
Shoes matter if you don't have nice shoes for everyone consider doing barefoot!
Also, see below my client closet options, and feel free to ask me about using any of the pieces.
My Client Closet
I offer dresses for women and a few options for kids. I am happy to have you try them on before the day of the session. Just email me to set up a time. Hello@thethreephotography.com