A good long sleeve solid snap shirt goes a long way. Western front and back yokes.
A - Hat Size: Wrap a tape measure around your head about 1/2" above your ears and across forehead.
B - Neck Size: Take a shirt that fits you well, lay the collar flat and measure from the center of collar button to far end of collar button-hole. The measurement in inches is your neck size.
C - Chest/Bust: Measure around the fullest part of your chest, under arms and across shoulder blades.
D - Sleeve length: Bend elbow up, measure from center of neck (back) to elbow and up to wrist.
E - Waist Size: For Belts - To determine your belt size, add 2" to your jean or slack size. For Slacks/Jeans: Wrap the tape measure over a shirt (not slacks) around body at the height you usually wear jeans or slacks. Keep one finger between tape and body.
F - Hip Size: Standing with feet together, measure around the fullest part of hips (usually 8" below waistline or at the bottom of zipper.)
G - Inseam Size: Take a pair of pants that fit you well, lay flat with side seams together. Fold one leg back and measure flat leg from crotch inseam down to bottom of pant.
H - Footwear Size: Order your normal street shoe size unless otherwise specified.