Making a Perfect 1/4 inch Seam
You may be making scrappy quilts, but one quilting basic never changes. You need to be consistent with your seam allowances, and they need to be an exact 1/4 inch.
If you deviate from the measurement, your quilt will have major problems. Pieces won't fit together and you end up struggling to make adjustments.
If your 1/4 inch seem allowance is only off a little, you may not think it is significant. However, by the time you get to a row, it can add up to a significant length. If you are only off 1/16th of an inch, and you are piecing 16 squares in a horizontal row, by the time you are done you will be off almost 1 inch.
Most quilters have a special foot they put on their machines, as pictured above, to help them with their seam allowance. Some machine feet are made so that you can sew on the edge of the foot and the seam will be 1/4 inch. Other machines let you adjust the needle position.
Most machines have markings on them, but I have always found them hard to read. You can also put pads of post-up or sticky-notes in front of the needle to guide the fabric, or use masking tape. These last options should only be temporary measures. If you are going to quilt, find a machine foot that will let you do it with ease. Most people tend to veer off the quarter inch seam line either at the beginning or end of the row.
Practice until you can sew a straight line and it is 1/4 inch from the edge of the fabric. You will save yourself a lot of aggravation if you learn to sew the perfect 1/4 inch seam.
HOW TO ASSEMBLE YOUR QUILT