When measuring your body, keep in mind that the measuring tape should be kept parallel to the floor. Also, make sure to take measurements in your undergarments, not over your clothes!

Bust
Wrap the tape measure underneath your arms, around the fullest part of your bust, with your with arms lying at your sides.

Waist
Lean slightly to one side. The little crease is your natural waist, and that's where you'll want to wrap the tape.

Hip
Stand with your feet together and wrap the tape around the widest part of your hips and rear. The tape should be snug, but not squeezing!