The adjustable seam guide of my vintage Singer 301 is slightly curved on the feed end. This really helps guide the fabric without snags. When I tried the note pad thing, the fabric kept catching on the pad. If I need to do it again, I'd look for the pad with the round edge. I've had good luck with the magnetic seam guides, but find that it helps to secure them with a piece of tape. One of the problems with attached seam guides is having to take them off to make HST, and other mid line stitches. The placement is easier if I take a sewn seam to measure, rather than using the index card. That's because I can't always remember if I have the guide set for a thread short of 1/4 or on the $. Even with the most diligent attempts, I still get wobbles. Most of the time, I view these wobbles as no threat to the quilt. If the meandering will be detrimental, I rip and correct. Detrimental could be too close to the raw edge, or sufficient to cause a domino effect with other piecing. Enjoy the process, but fret not the method.