Bust

Measure over the fullest part of your bust, in your best-fitting bra

Waist

Measure at your natural waistline, at the narrowest point.

Hips

Stand with your legs together and measure over the widest portion of your hips: this typically includes the fullest part of your rear.

Inseam

Lay your favorite leggings on a flat surface and measure from the crotch downwards, following the inner seam.