I pin parallel to the stitching line -- OUTSIDE the seam allowance. If seams are pressed in opposite directions, this should be sufficient. I also keep my Clover seam ripper on my machine deck to use as a stiletto with a little pressure. It is so fine that it goes right under the presser-foot to keep seam in place, yet it can be pulled out just before the needle goes down. I shouldn't say this, but I've never hit the ripper point with a needle (please don't let this jinx me!). I haven't tried glue, but have pinned like this: put a pin through the seam intersection of top piece, then continue the point through the intersection in the bottom piece. with the pin at 90 deg. of the fabric, pin (perpendicular) just before and just after the seam and parallel to the seam "boxing it in." Remove pins just before you come to them. For really tough intersections, do this AND do 4-6 basting stitches, then check accuracy before doing final stitches. Remove basting after stitching.