The way I learned in Homeec is to pull a thread across the grain, and cut along this thread. This gives you a true edge. Then when you place the fabric down smooth (selvedges together) if that edge is not lined up (the selveges) on the end, you need to stretch the fabric on the bias all the way down until it is straight. This way there is no distortion. Now since I have been making quilts and my pieces are so small, not a problem, however if you are making borders, can be a problem if the weave is off.