Shooting etiquette

This post inspired by comments I made here.

Suppose you are out shooting with a friend, and you borrow his rifle to shoot. Here are some suggestions to keep in mind as far as proper etiquette is concerned:

1. Avoid pointing his rifle at him. 
2. Ask before using his ammo.
3. If he gives you a whole box, and says "go for it" (or similar), do not feel required to continue to ask if it's OK to shoot the ammo. 
4. If you like shooting that gun, and are smiling because of it, let him see you smile. 
5. A real rifleman will not mind if you make adjustments to his sights. A competitive shooter might. A whiny perfectionist who cannot shoot will complain about you adjusting his sights. Know which one your friend is. If in doubt, ask if you can adjust the sights. 
6. It is generally poor form, after shooting another person's rifle, to denigrate that rifle. 
7. It is OK, however, to state: "man! That thing has some kick!"
8. It is always good form to state that the rifle was surprisingly accurate, or similar. 
9. Do not drop, or otherwise damage the rifle. 
10. Bring a friend next time. Bring your rifle, too!

Note: almost all of the above will apply to handguns and shotguns - save the sight adjustment part.