When i took a class the teacher told us to start on the line about 3 or 4 stitches and then slightly vere off the line towards the point and sew till you get about 3or 4 stitches then go back on the the line.this will give you a little extra when you press open and then you can trim.
Works for me everytime.
I think MadQuilter described this also.
Gale