Here are several methods I use that work for me:
1. I sew a few stitches right at the point where they need to meet. If they are oK, then I sew the whole seam, if not I pull them out and try again.
2. I use elmer's school glue to match the seams, press it with a hot iron, then sew the seam
3. I use the fork pins to hold the seams together on either side--you can see them here:
http://www.123stitch.com/cgi-perl/it...l.pl?item=C240