Trace the pattern onto the fabric.
Make sure to trace the circles on the lines: they are to mark when to switch the stitch widths.
Pin the fabric along the traced lines.
This is to make sure the lines are matched precisely back and front.
Pin along the dart to secure the fabric together.
Pin an extra pin at the end of the dart to ensure the fabric does not move around while sewing.
Remove the pins used to align the dart.
Check if the lines are aligned by inserting a (green) pin from one side of the traced line. It should come out on the line from the other side.
Start sewing, using the largest stitch width.
When the needle reaches the halfway mark (the small circles on the dart lines on the pattern), change the stitch size to one lower.
While changing the stitch size, make sure the needle is down.
When the needle reaches the end of the traced lines, run a couple of the stitches and then stop.
Leave about 2″ of threads and the cut the threads.
Tie the excess thread twice.
Make sure the knot is tight and not to leave any space from the fabric.
Press the dart.
Flat sides first.
Use a towel or ham to press the curves.
Examine the darts. The top of the sewn fabric should form a smooth line.