Best place to learn rules of PvP modes?

[Risvertasashi]

Google "PvPaissa" and join their discord and check out their guides. They also have job specific help channels.

That said, be warned you may see salt about yourself if someone in the same match decides to complain.

Edit: Also if you're just looking for the utmost basics, there's the official guide at https://na.finalfantasyxiv.com/lodes...uide/pvpguide/