Mens
Chest size: The measurement should be taken beneath your armpits, around the widest part of your chest and shoulder blades. Keep the tape measure horizontal.
Waist: Put the tape around your natural waistline, which should be close to your belly button. Put one finger between the tape and your body before you measure.
Outseam: This is measured from the top of the waistband to the floor with feet together standing up straight. You might find that is most easily measured on a pair of pants that already suit you.

Ladies
Bust: Measure under your armpits, around your shoulder blades, and over the fullest part of your bust. Don't pull the tape measure too hard.
Waist: Measure around your natural waistline. This is the narrow part of your waist, approximately an inch above your navel. Relax and breath out before you measure.
Hip: The hip should be measured around its fullest part (about 8 inches below your waist.