when we had them done a couple of years ago we dressed in what suited us personally - everyone in jeans then DD1 had a soft but still strong (ITMS) blue tshirt, DD2's was a very strong and bright pink, I was in a sapphire blue and DH in red. The colours looked fine together, but best of all was the effect they had on your own facial colouring, eyes etc. We also took fairy dresses for the girls to change into so there are photos of them "properly" dressed, and then cute dress up photos.