It varies depending on the music genre and is quite subjective. For instance, when I was younger, moshing was all about aggressive pushing and slamming into each other, especially since I was into crust punk, punk, death metal, and metal(all kinds/thrash). There was this "unspoken rule" that if you fell or got hurt, it was your own responsibility. Sometimes, it can be unpredictable—you might get shoved and find yourself on the ground, or in worse cases, you could get injured. I remember my first time in the pit; I ended up with a broken nose when I didn't see a big guy's arm coming down on me. To this day, my nose is still crooked, but I like to think it adds character! Each sub-genre seems to have its own preferred style, whether it's dancing in a circle, everyone moving together, or getting more aggressive. Because of this variety, it's difficult to establish a set of rules. It's best to observe how people react during the first song to gauge the vibe of the show and then add your own style. If you're looking for distinct characteristics, they definitely relate to the music; for example, a New Found Glory show is vastly different from a set featuring death metal bands. Each has its own unique approach to the pit, paying its own "homage" to the experience.
Ultimately, it’s up to you, as everyone generally agrees that the safety of others shouldn't be completely jeopardized. It’s frustrating when a show gets ruined by crass individuals who cause problems, especially when you've been eagerly waiting for the performance to unfold.
Been to many shows and man is each one so different.