Measure against your body rather than over your clothes at it will give a more accurate result.
Measure under the arms at the fullest part around the bust horizonatly
Measure around the natural waistline
With the feet together measure around fullest part
4. Inside leg:
In bare feet take the measurement from the top of the inside leg and measure down the inside leg to the floor
With bare feet together measure from the top of the head to the floor