Using a soft measuring tape, start with your feet shoulder-width apart. If available use a mirror to ensure the tape stays parallel with the floor from front to back. 

Bust:
Measure under your arms and around the fullest part of your bust (usually where your nipple is). If you intend on wearing a bra with your garment, measure with a bra on. If you plan on going braless, measure without a bra.

Waist:

Measure at the smallest part of your torso. If you do not have a smallest part (this is completely normal!), bend to one side and find where your body folds. This is your waist. Tape should feel snug and comfortable but not pulling or falling down. 

High Hip (Corset Tank Only):

Measure the circumference of your torso 3'' below where you measured your waist. 

Full Hip:

Again with legs shoulder-width apart, find the fullest point of your hips including your bum!  Make sure the tape stays parallel to the floor when measuring. You basically want to measure the widest point of your lower body here (for many of you this will be at the upper-most thigh and mid-bum point).

Bust to Waist:

From the side of your body, measure the distance from your nipple to your waist

Waist to Hip:

From the side of your body, measure the distance from your waist to the fullest part of your hip.