Measure loosely around the fullest part of your bust, with the tape straight across and your back, bringing it to the front. This is your bust measurement.
Wrap a measuring tape around your natural waistline, making sure to keep the tape parallel to the ground. This is your waist measurement.
Wrap a measuring tape around the fullest part of your hips, making sure to keep the tape parallel to the ground. This is your hip measurement.
Slip on your favourite pair of jeans that fit you best. Take your tape measure and carefully measure the length of from the crotch seam to the bottom of leg. This is your inseam measurement.