Make sure you are standing straight, looking forward and has a natural posture. Your feet should be directly under your hips with your feet parallel but not touching.
For the most accurate measurements wear a leotard as this will ensure the most accurate measurements.
Ensure that you breathe in and out naturally to avoid the tummy suck and assure a comfortable fit.
Before you start taking measurements ensure that the flexible measuring tap is lying flat. When taking measurements make sure the measuring tape isn't too tight or too slack.
The inseam should be where the leotard leg line meets the tights or the top of the leg.
Measuring girth is the most important measurement. If you are in between sizes, allow girth to be the guiding measurement to make your judgement.