Chest:
Measure around the tight est part of the chest, keeping the tape horizontal to the pavement.
Waist:
Measure around the narrowest part of the waist, keeping the tape horizontal to the pavement.
Hips:
Measure around the bulkiest part of the hips, keeping the tape horizontal to the pavement.
NB: If you are borderline between two sizes, order the smaller size for a tighter fit; If your measurements for chest and waist correspond to two different suggested sizes, order the size indicated for your chest measurement.