If possible, it’s great to wear tones that go together within a family e.g. all pastel colours or all darker colours. I’d rather you avoid white tops but if you especially wanted to wear eg a white linen shirt then it’s best if you all wear white on top. It’s also fun to match backgrounds to outfits so if, for instance, you have a lovely peeling garage door in olive green then we might pick a grey/green shirt or dress to compliment the background, especially if you or your child have green eyes.
You may want some photos that are more formal with smarter clothes e.g. in front of your house, and then some that are more playful with more vibrant and casual clothes when the children are, for example, lying in a wild meadow. For small children, especially girls, we might go for something like a favoured tutu as well!