Ten Rules of Mosh Pit Etiquette
7. Learn your basics
Any sense of format to moshing can easily be tossed out the window depending on the size of the crowd, so often trying to adhere to a style is futile. Still, it does help to know a little bit about what movements are associated with what styles of music. Punk and metal pits used to be a bit more distinct from one another, the former stemming from skanking and circle pits, the latter from slamdance and showy fist flails. Depending on the show you're likely to see some hybridized version of all of these, but occasionally the band will literally dictate the format. (Trash Talk often calls explicitly for circle pits on particular songs, saying that's how it's done in California.) If someone calls for a wall of death, know ahead of time how to prepare.
6. Know when the pit begins and ends
There's no clear-cut point at which the pit is going to start off, and the initial moments in the center of the floor during the opening bands can be tense with potential energy. Some riff or blastbeat will just seem the appropriate time to set things in motion, and everyone will just know it's time. If you've taken upon yourself to be the one who lights the fuse, recognize who else around you seems like they're similarly prepared. Simply leaping into someone else ought to be enough to signal to others it's time, but especially in a smaller crowd, make sure you know who that person should be. Don't be the one to miscalculate and fling an elbow during a band's slower droning section.
5. Throwing things is generally frowned upon
Tossing water or beer into the air is a pretty common practice, but don't throw a full water bottle or anything heavy. I once got clocked in the teeth with an open but full can of Surly Furious, which both made a hefty impact and splashed all over my face and clothes. Getting splashed is somewhat of an inevitability, but a full can of beer is like a couple of pounds, and that shit can cause some damage. Remember: Houdini died taking a punch he wasn't ready for. Any blows you'll sustain should be fine if you're prepared for them, and an airborne assault can easily catch you off-guard.