Jinny is often asked how to achieve even stitches when hand piecing. She replies:
It is all a matter of maintaining proper tension. You may be familiar with the “sewing birds” they had years ago. The birds were attached to a table and were used to anchor the fabric while one hand held the other part of the fabric at a good tension. The free hand took the stitches.
Tension on the fabric is of the utmost importance. Without proper tension, your stitches will be too loose or too tight. It is the same thing as quilting. Without a hoop or frame your stitches may be too loose or too tight. When I am hand piecing, I hold the fabric in both hands and I pull the hands slightly away from each other, creating tension on the fabric. The hand with the needle “gathers” the fabric onto the needle. I constantly maintain the tension as I sew the stitches.
For complete information on hand piecing and much more, see Jinny’s book, Quiltmaking by Hand.