Above Bust
Measure above your bust, under your armpits

Bust
Measure around the fullest part of your bust

Waist
Measure around your natural waistline at the smallest part

Hips
Keep your feet together and measure around the fullest part of your hip 

Length
Measure from the middle of your shoulder, making sure you measure over the fullest part of you bust. Ensure you are standing straight and not bent over.