Measure around the fullest part of the head.
Measure a shirt collar that fits you well and measure from centre of button hole to far end of opposite collar.
Chest - measure underarms and across shoulder blades. Bust - measure at fullest point of bust.
Measure around your natural waist line.
Standing naturally, measure around the fullest part of your hips.
Measure similar pants that fit you well. Lay them flat, and measure along the inside leg from the crotch to the bottom of the leg hem along the seam.