Begin with the most important step...

MEASURE YOUR BODY
Only basic body measurements are needed to determine your pattern type and size. Remember to wear proper undergarments and shoes when measuring. Also, make sure the tape measure is held snugly and firmly (not tightly) against your body and is always parallel to the floor for circumference measurements.

For Misses’ and Misses’ Petite:
BUST- Measure around the fullest part of bust and straight across back (1)
CHEST- around body above fullest part of bust (2)
Waist- around body at natural waistline (3)
HIP- around body at fullest part—usually 7-9" (18-23cm) below waist (4)
BACK WAIST LENGTH - from the most prominent bone at base of neck to the natural waistline (5)
HEIGHT- measure (without shoes) standing against a wall

Tips : I advice you to measure by centimeters.