Depends on if u want a random look or a more control look..I also have to have the material matching..but usually we pick the same sort of material when we buy..so u well be surprise how most of it matches.I like to have the center piece larger..but I also like to mix up the angle they are used..some I have done all at a corner to corner angle..others straight..really they are just fun to play with.after they are finish ..they never stay here very long as my family really likes all the color ..also I have made one with the larger strips in the rag style..it turnout well..just have fun..for the back..if I want a size before I start..use old sheets cut to the size square u want..sew the material to the block as u go..u can use a lite batting when u do this..or none at all if u want a lite cover..