My suggestion is not to stress out too much about the evenness of your stitches. For me, anyway, it seems to work to concentrate on the pattern, and eventually I get into a rhythm, and the stitch length starts to take care of itself. I also feel that if you use too slow a speed on the machine, things get worse. You have to find your own "sweet spot", where the speed of the machine and the speed at which you move the fabric are in synch.