Having old favorites tailored is a great way to extend the life of your wardrobe. Here are the basic rules of thumb:
Pant cuffs should hit just slightly above the shoe; width of cuff should be about 1 ½" wide.
Suit jacket sleeves should hit just at your wrist bone and allow about ¼" of your shirt or blouse cuff to show.
Skirt hemlines are a matter of personal choice, but the most flattering length is just above or below the knee, at the bottom of your calf or at the ankle.
Waist bands should allow enough room for two fingers.