You want something that looks good, the first thing it needs to do is fit, we take that seriously.
Below this text is a sizing chart, so… get naked (or scantily clad,) then grab a fashion tape measure…
HOW TO MEASURE
BUST
Measure around the fullest part of your bust. Under your arms, across your back and around your bust, ensuring the measuring tape is straight.
UNDER BUST
Measure just under your bust at your ribcage, where your bra strap would sit. Ensuring the measuring tape is straight.
WAIST
Measure around the smallest part of your waist, near your belly button and under your rib cage.
HIPS
Measure around the widest part of your hips. Starting at one side, wrap the measuring tape all the way around your buttocks, ensuring it is straight.