As a general rule, keep the tape measure firm but not tight around the point that you are measuring. If you are measuring yourself, we recommend taking a couple of measurements from each area in order to average out the changes in your posture whilst you are measuring.
To measure the bust, measure the body at the fullest part of the bust. Keep the tape measure as level as possible around your back and under your arms.
Measure around the narrowest part of your body, which is above your belly button but below your rib cage.
Go round the body at the fullest point of the hip line. This is usually around 9" below your waist.