7. measure your waist

Measure the circumference around your natural waist. The natural waist is the smallest point of your waist. For most women this is just a little above the bellybutton. 

Measure also the circumference of your waist further down, where you can feel your hipbone standing out a little (= low waistline).

For both of those measures make sure the measuring tape is straight and parallel to the floor. If you are 

alone, use a mirror and check that the measuring tape follows a straight line, also in your back.