Height
Measure from the floor to your head.

Arm length
Measure from your shoulder to your wrist.

Bust circumference
Measure (parallel to the floor) the fullest part of your bust.

Waist circumference
Measure the narrowest part of your stomach.

Hip circumference 
Measure (parallel to the floor) the fullest part of your hips.

Inseam girth
Measure from the uppermost part of your thigh to your ankle.