You can do just fine without a guild or in a non-PK guild. The important thing about PvP server is reputation and networking. Meet players from other guilds, learn about their enemies, hunt them together, don't be a dick. If guilds know you're an asshole, some people will go out of their way to hunt you down and make life miserable.
PvP is really about watching your back and protecting your goddamn neck
[You must be logged in to view images. Log in or Register.] get used to doing /who often to find out if enemies wandered into your zone.