Measure the circumference by keeping the tape up under your arms and around your body.
Measure at narrowest circumference.
Shoulder and arm length
Measure from the base of your neck along your shoulder and your arm down to your wrist. Bend elbow gently.
Measure from the most exterior spot of your shoulder along your arm down to your wrist. Bend elbow gently.
Close your feet. Measure at the broadest section of your hips.
Close your feet. Measure from your crotch down to the floor. Stand up straight. If possible, have a second person take the measurement.
Measure your height in a door frame or against a wall. It's easiest with a ruler placed on top of your head. Make sure you don't look up or down while marking against the vertical surface.
Underneath the chest
Measure roughly 1 cm underneath your chest around your body.
Wrap a measuring tape around your dominant hand just below your knuckles (excluding your thumb), and make a fist.
Take a measuring tape and run it around your head at about 2 cm (ca. 0.8") above your eyebrows. It should slope down a little bit towards the back of the head. Once you have it positioned correctly, pull it tight and take measure.