If you don't care about the builds/experience levels of other players in your group, area or text chat is a good way to find members for your group. Be aware that you will end up with people who have never done the dungeon before, or people with 531 cp who completely fail to fill their role because they are using pvp gear/skills. Finding good people to run with is hard because most dedicated players already have groups they run with that can complete the content easily and efficiently and have been playing for multiple expansions together.