For my full family photography sessions, I offer pages of information on what to wear. But these front steps photos are meant to be much less staged. The idea is that they're very real and natural photographs of you and your family.
So long as the clothes are decent, not too scruffy, and well-fitting, the session will work well. It's usually best to avoid typeface and big logos - but if that upsets a teen with a Nike obsession, who am I to argue?!