I was in a similar situation, and started by looking at PvE servers in my time zone (EST). On I think WoWWiki there's a listing of servers sorted by time zone and realm type.
Then I opened up the server forums and checked out the different servers progression and the guilds that were recruiting. One guild really jumped out at me, I talked to an officer and asked some questions, applied, and turns out the guild is awesome.
A lot of it is a shot in the dark though, no matter how much research you do into a guild you're not going to get the whole story until you get there. Good luck!