Each way of shashing produces a unique look. Such as a single color where you really want all the seems to blend creating an over all uniform appearance. Or deliberate constast such as "attic window" which is there you attach two different sashing matericals one to the left and the other to the bottom side and miter them together. Then when you sew all your blocks together it gives the entire thing a three dimensional appearance. Can you tell the last is my current choice? There is one true way as others have mentioned.
Another way is to sew four strips one to each side of the bock and have squares of a different color in the corners. Simply run a search for sashing techniques and you will find lots and lots of ways. :D