I watched Carol Doak on Craftsy website and she had a fabulous trick of putting the blocks together. It is hard to described but she would pin her blocks every 3 inches and then use a long stitch (3 to 3.5) and use that as basting stitches in place of the pins. She would open the block to check to accuracy and if needed unpick and baste again. If everything lined up she would go back and sew the entire length of the block at 1.5. Also she left the paper on until the entire quilt was assembled.
I highly recommend watching her video it is so worth your time and money. It has made my paper piecing so much easier an accurate.