Best thing I would do is to start playing people on live and seeing how they play with your gaming style. Are they more into sniping, running and gunning, grenade whoes, etc. Just take your time and once you party up with some folks and win, start asking them if they want to be in a clan. Once you've agreed, make an icon that you all would have and then stay party'd up for all games.
Unlike halo 2, halo 3 doesn't have the nice clan feature so this one of the only ways you'll be able to do it. GL