Best advice I can tell you is just get to know the members of various guilds by grouping and asking them questions. Then see if you "fit in" with members of a certain guild. Once you have done this, learn what that guild is about...is it a guild of friends just to have thier own chat channel, is it a role play guild, is it a guild that raids, but is not manditory or one that requires its members to attend?
Just treat looking for a guild the same way you would make new friends.