I always recommend to wear clothing you’re comfortable in. Clothing that you can move and play in! That goes for the parents as much as the kiddos. The idea of having a Mama not be able to play with her kids because her dress is too restrictive or precious makes me sad! If your little girl is in a dress make sure you have cutie bloomers or shorts underneath so she can twirl and spin and jump without the worry of underwear or diapers showing.
One good rule to follow is to have Mama in something flowy and patterned ( fabric and clothing styles with movement can add a fun element to photos ) then kids in either solid colors or simple patterns like stripes and spots and Dad in solid neutrals.
Make note of the different patterns in your outfits and make sure they compliment each other rather than create visual chaos! Of course if you prefer to have your partner or kids in patterns that works too! Often Mother’s have the hardest time finding something they like for themselves so start there and build everyone else around that.
In regard to color palette generally lighter more pastel colors work in most locations. Light colored snuggly cozy fabrics are always great for newborn sessions and black sometimes doesn’t photograph well when indoors.
I'm also a big believer in the idea that rules are meant to be broken. If you want to wear a bright pink fluffy dress to your beach session do it!
Lastly try to avoid shirts with graphic logos or text as it can become distracting and can pull focus away from faces.
Feel free to email me with your ideas if you are looking for a second opinion when it comes to putting outfits together.