Find a random guy on the server, hang out around with him. Don't mention anything about running a faction or what not. Scope him out, and if he is cool ask him to join. Talk to some people in other factions, see if they are discontent with their leader. Offer them what they are griping about in exchange for joining you. As for betrayal what I usual do is keep dead drops all across the map. A few iron gear here, some diamonds there. In case I am looted/betrayed, I have the gear I need to get back on top and launch a counter attack.
Top notch advice there m8