Math. And fittings. I first took Nina's measurements: bust, shoulder width, upper arm, waist, hips, and back length. I made a swatch with cables included. Because Nina wanted the dress heavily cabled, I just had to add up all the stitches in the cable charts and then add reverse stockinette stitches between cables until everything added up to her upper bust measurement. As I worked my way down the dress, I used the fields of reverse stockinette to do my increases and decreases, guiding the width of the fabric to match Nina's measurements. Periodically, I had Nina try the dress on to make sure I was on track and could go forward to the next section. At the hips, the dress was flaring out a bit, so I had to frog 2 inches.
Nina wanted a very cabled, close-fitting dress (2 inches of negative ease, I think), and she's very happy with the result.
P.S. Adding/subtracting the same number of sts on either side of a cable keeps the cables in a straight, vertical line. I needed to avoid any bowed-out lines in the bust, which would make her look bustier.
For a project like this, there's really no substitute for swatching and math.
Last edited by dancejunky : 12-09-2012 at 12:15 PM.
Reason: more detail