Hi, As one of the more experienced hand quilters on the site I would recommend stitching about 1/4 inch inside the outside edge of each different part of the design. The pattern you are using uses a different fabric to create the effect of each shape. You might want to quilt a small motif in the middle of each square. I have a collection of cookie cutters that provide interesting simple patterns for such a project. I would also use at least one curved pattern, chain etc. in one of the borders. From the back your quilt will look great also as piecing will not interfere with the effect of the quilting.
Have fun.