This is a question I get at about every session. I just finished a FAQ for clients that book and in there I touch on this. I came across this great article over at a photoboard that I belong to and wanted to share. : )
Attached is a picture from our family session this year that shows how we dressed with coordinating, neutral and vibrant colors. I love the mix of neutrals and color in our outfits. I think it turned out quite nice!