ingame General chat makes it possible to recruit players more easy. Make sure however you have a chat moderator who can easily ban players from General chat, should they brake General chat rules. Chat control of alliance chat is not needed: the alliance leader can kick members, so if someone...
make it possible to declare war to other alliances, but also make it possible to decline an invitation to alliance war, at the cost of points/ranking. Make it rewarding to win alliance wars from stronger alliances than yourself.