Origami paper comes in a variety of colors, sizes, and textures and is available in most art and stationery stores. Traditional origami paper is thin, strong, and holds a crease well. It is usually colored or patterned on one side and plain on the other. Almost any available paper can be used: a magazine page, gift wrap, or notebook paper.
To make a crane (and most other origami figures), the paper must be square. It's easy to make a perfect square out of any rectangular sheet of paper. Lift up the bottom corner of the sheet and fold it diagonally so that the bottom edge meets the side edge of the paper. Cut off the strip of paper that is left at the top, and you have a perfect square!
It's best to fold your first cranes with paper that is at least five inches square. Eventually you can make them very tiny. Sadako made many of her cranes out of candy wrappers, and some were no bigger than a rice kernel. She folded these with the help of a toothpick.