Natalie at Craftzine has posted beautiful instructions on how to make a hand-sewn hem. In her example, she mends a skirt whose hem has come partially unraveled, but you could also use this technique to shorten or lengthen sleeves, pants, dresses, or skirts. If the hem edge isn’t neatened up with a zig-zag finish or folded under, then you will need to prevent unsightly fraying by folding it under a very small amount prior to pinning.