It's your actual body measurements that count, not the garment size you may normally wear.
Please do not exaggerate measurements!
Head: measure all the way around the head
Collar: measure all the way around the neck
Chest/Bust: place tape measure loosely under the arms
around the fullest part of the chest
Waist: measure around the natural waist,
keeping the tape measure slightly loose
Hips: measure around the fullest part of the bottom
Inside leg: measure from crotch to hem
If in doubt, please e-mail or call for advice.