Look on Pinterest and search for quilt backs----lots of examples will come up. I piece almost all of my backs. I find it easiest to divide the back into thirds----they don't have to be equal in size. I usually put my leftover blocks into the middle third, then use complimentary solids or prints in whole pieces for the other two sections/thirds. Once you do one or two ideas will start coming to you and you will see how easy it is.