I discovered a magnetic Quilter's Seam Guide by Dritz Quilting it was less then $2.00 @ joann's. All you do is measure where you want it and it will "stick" in to place. it gives you a wall to keep your fabric aginst while you sew. It is working great for me and the added plus is it is adjustable to what ever seam allowance you want.
Happy quilting.
G