When joining eight points, sew the first four pieces together and then the second four, and finally one straight seam will join the two halves. Begin by laying the four pieces for the first half out onto a table or your lap.
Pick up piece A and, with right sides together, pin it on top of piece B. Starting at the outside edge and sewing towards the center, sew just to the point of where the seam allowances on the piece would cross, and take a small back-stitch. Do not break the thread.
Take the pin out, open up the two pieces and gently finger-press the seam towards the right.
Now take piece C and place it, right sides together, on top of piece B. You should be able to feel the ridge from the seam allowance with your thumbnail. Carefully bring the needle directly through the end of the last stitch and through the base of the seam allowance. Take a back-stitch along the ridge and then continue sewing to the end.
Check to make sure that the point on piece B is securely bounded by pieces A and C as shown. If this point is not neat and sharp at this stage, you will not have sharp points when all eight are joined.
With the right side facing, finger-press the seams towards the right. Pin piece D on top of piece C.
Using a new thread, bring the needle all the way from piece A, at the exact point where the first seam ended, and through the bases of the three points and onto piece D.
Back-stitch along the edge of the seams and continue sewing the last piece.
Sew the remaining four pieces in the same manner so that you now have two halves. Check to make sure that the points in the middle of each half are securely bounded by the points on either side.
Place the two halves together with right sides facing each other, making sure that the points of the center piece in each half meet exactly. Place a pin through the point, with the point of the pin coming just below the bulk of all the seams of the points.
Sew from the edge towards the center. As you reach the center, carefully pull out the pin, bring all the seam allowances towards the left and sew up to the seam line, making sure not to catch any of the seams in the stitches.
Back-stitch at the center and then pass the needle through the base of the seams. Now pull all the seams towards the right, take another back-stitch right next to the seam and then continue sewing across to complete the seam.