HOW TO PHOTO WELL
1) Don't be eating. Or chewing. A decent photographer knows better than to take photos of people at a meal but there are very few decent photographers left. Every stupid face you've ever had photographed was caused by food.
2) Don't be talking. Wait, let me rephrase that. DON'T BE TALKING. Every ridiculous face you've ever had photographed was caused by you not shutting up when there was a lens angled at you.
3) Everyone has a double chin. A photographer above you will almost always have better luck than a photographer below you. You may not have a good side, but either side is probably better than dead-on.
4) You look awesome backlit if they know what they're doing, and like ass if they don't. If they do, they'll take a while. If they don't, you're fucked. Suggest that you face the sun.
5) One of the Renaissance sculptors observed that our faces are at their best and most honest when we are about to speak. When there's a camera pointed at you, think of something clever to say. Then see (2).
6) Shoulders back.
7) Think of something funny. When I photograph portraits I crack jokes non-stop. Fake smiles are useless. Real smiles are priceless.
8) Understand that your self-image exists solely for one person but that photographs exist for everyone. You look much better than you think.