In order to get the best fit you need the right measurements. This generic guide will help you through the measuring process.
How To Measure:
NECK/COLLAR - Starting with one inch of slack, measure around the base of the neck to accommodate for additional comfort.
CHEST TO FIT - Arms down, measure around the fullest part of the chest.
BUST - Measure the bust across the fullest part.
WAIST - Legs together and arms down, measure around the natural.
SLEEVE - Hands on hips, measure from the base of the neck, across the shoulder, down the elbow then finally to the wrist.
INSEAM - With legs slightly apart, measure down the inside of the leg from the crotch seam to the botton of the hem.