You need a security token and unique password.

[sirdayne]

With the current epidemic of players having been compromised by RMT spammers, I can't stress this enough... for current players and anyone considering playing ARR:

1. Get a security token.
2. Use a unique password that is easy to remember but hard for attackers to break. Generally speaking, the more complexity and length a password has, the harder it will be to break.
3. Do not use that password on any other site.

If you want to bring your friends into the game make sure they also follow these steps. It is better take take precaution now. RMT are after any account they can break into and spam from.

Edit: Ignore previous example webcomic.

Do NOT use that example ! That's rubbish, any hacker worth his salt will break it rather easily. That comic is wrong and has been proven wrong by many security experts since it's publication.