Step 1. After being cut or torn at the store and then washed and ironed
at home, fabric is almost never straight and ready for rotary cutting. It is imperative that you start with a straight edge across the width of the fabric.
Bringing selvages together, allow fabric to drop in front of you.

Keeping selvages even, scoot fabric along with your fingers until it falls perfectly straight. The raw edges where fabric is torn will probably not match up.

Step 2. Lay fabric on cutting mat with folded edge toward you and raw edge to be straightened facing right (left-handers facing left). Place 6" x 24" rotary-cutting rule on fabric, aligning one of the crosswise measuring lines along the fold. Pressing down firmly on the ruler with your left (right) hand, cut upward, or away from yourself, along the rule edge. Some people prefer cutting part way, stopping the cutting motion but not lifting the cutter, moving the left (right) hand up, then finishing the cut.

Step 3. Turn cutting board around so that newly straightened edge is facing left (right). To cut strips, find line on rule to match width of strip desired. Place this line exactly on cut edge of fabric and cut strip.

Perfect squares: Align 1 or more strips of the same width and trim ends to get an even starting point. Make cuts the same width as strips were cut.