Here is a tip that I learned and it will save your sanity, no matter which method you use to piece the block: Decide which fabrics will be the 2 last strips you sew on. One will be vertical and one horizontal (mine are usually on the sides which are dark). ADD 1/2" TO THE WIDTH ON THOSE STRIPS when cutting, before piecing. In other words, if you have cut 2 1/2" strips throughout, cut these 3" wide. That extra 1/2" (you could do 1/4" inch if you are a more experienced quilter) will allow you some "wiggle room" to square up your block (on the 2 dark sides) should your block be slightly too small. Happy piecing!