Step 1: Measuring your waist
Wrap the tape measure snugly, but without cinching, around the natural indentation or break at your waist. If you can't find this curve, bend to the side and the crease will show you where to measure. This is your waist measurement. Write it down, you'll need it in a moment.
Step 2: Measuring your hips
Wrap the tape measure around the fullest part of your hips, but not your bum area. Use the mirror to make sure the tape measure is straight completely around. The tape measure should be slightly snug (but not overly tight) and parallel to the floor. Write this down as well.