I added a comment with a couple of my own suggestions.
Another common thing I use with people is to get them to twist at the waist. This narrows the waist.
People need to watch bringing their chin down like you suggest. If they havenâ€™t stretched their necks like you suggest, they will create a double chin. I often have to tell subjects to raise their chins.
Another tip is not to press your arms against your side, especially for women, because it makes them look wider.