I showed my chickens at the county fair for 4-H. It was fairly informal, and I don't know what sort of shows you are looking into. All shows depend on the judges style, so don't base everything off of me...
For showmanship, we would each hold our calmest chickens, and the judge would walk down the line, and ask each of us questions about our individual bird, Chicken care, and the history of the chicken breed we held. As a tie-breaker, he would ask us to name all of the varieties and breeds of the chickens other 4-H'ers were holding! Showmanship depends much less on the bird than the knowlege of the owner.
For the breed shows, the judge would look at each individual bird or pair, and look for good conformation and type in each breed. He would look at the eveness of the feather coloring, the condition of the bird's plumage and comb, and how they compared to other birds in the line up, as well as the breed standards. (He said my bantam Brahma's had 'too round of heads'!)
Showing is fun, and I learned so much. Plus it was a chance for me to show off my chickens to the public!