This is what i did,. using 6 1/2 inch squares
http://www.quiltingboard.com/t-103513-1.htm
You can measure the print on the fabric to determine what size square would show the fabric pattern off to best advantage, then cut all the squares to that size. The corner square is just half the size (or less) of the main square, so if you cut 10" squares, the corners would use a 5" (or less).