First measure the amount you want to shorten it by and cut the excess off (leave enough for the hem!). If you are going to use a sewing machine, use the spare bit you have just cut off to play about with the tension, foot pressure, etc until you have a result you like. The trick is to use not a completely straight stitch, but a slight zig-zag stitch, as this allows the material to stretch as required in wear. If you are sewing by hand, use an over-and-over hemming stitch which picks up the two parts of the garment to be hemmed alternately. This allows for flexing in wear.
Shan Parfitt, November 2007
