When hand piecing, you never cut through your stitching line. That's why you can't strip piece if hand quilting. Machine stitching can hold up to being cut, but not hand stitching.
It is traditional to mark the sewing line on your patches, and then to hand sew starting 1/4" in and ending 1/4" from the edge, backstitching at start and end. Jinny Beyer, who is famous for her hand piecing, does not mark the sewing line on her patches. She eyeballs the 1/4" seam (and sometimes checks with a fingernail). Later on, if she needs to adjust a seam, she simply re-sews it if the first seam will be hidden or undoes and re-sews if necessary. If you can get hold of one of her DVDs or videos on hand piecing (check your library), she does a great job of showing how you can hand piece very quickly.
When hand piecing, be aware that you piece with only a single thread.