For jacket size measure the chest under the arms (not too tight - leave a little room for movement. Insleeve is arm from wrist bone to armpit
Waist is one inch below the belly button (where we recommend dress pants are worn). Outseam is from the spot you measured the waist to 1 inch above the floor (in socks).
Neck is around the neck, a little loose for comfort but not too loose. We also take your jacket size into account