-Patterns are great so long as you're not clashing with each o t h e r. If she's wearing a floral dress, he probably shouldn't wear a plaid shirt.
-Skirts/dresses/bottoms that are flowy/comfy vs. too fitted/stiff are flattering, great for showing movement, and allow you to sit/move/pose more freely
-Consider bringing accessories to play with that give us options like hats, scarves, sweaters, jackets or a blanket to sit on or wrap yourselves up in.
-Think about your feet. Wear footwear that suits the setting
-If in-studio and going shoe-less, bring neutral socks if you're not going barefoot.
-More maternity, wear something fitted above the belly or empire-cut, it's more flattering, less boxy. Wear stretchy or flowy fabrics as opposed to non-stretch.
View my Pinterest board here for suggestions for you and your partner to choose outfits that flow nicely together here: https://pin.it/4Kk5UN7zj