Remember, when cutting jelly rolls, it's width of fabric (44" or so). If you are using a scissors to cut strips...mark with chalk and cut on the outside of the line...that's where the ruler line is.
If I know I have a good cotton fabric (don't throw stuff at me)...I tear the fabric. Some top printed fabrics (especially dark prints) do not do well with tearing them...the white base will show through. Once I have the fabrics torn, I spray with water, let them rest and press the strips...pressing them damp, pressing from the center out to the torn edges will, if it's good cotton fabric, reset any distortion from the tearing. If the fabric has any polyester in it..this does not work well at all.