salon printing is one manner . both vertical and horzital images are placed on a 16 X 20 board, but with all prints hanging vertically. this makes a show easier to hang. I suggest that my students use the same size board, images can be of varying sizes ; as the print should dicate the direction and size. This gives a nice unifrom look to the presentation. Then people do not have to turn the boards around to look at each print as each board is going to the same way.