Getting someone on the inside. Unless you think you can sway someone already in the ranks to your cause. It may take a while, but it's either that or hoping you can spy on them enough to figure out what is going on by intercepted transmissions and movements.

There's also playing tourist. Have everyone new you trust wander around and ask questions. Learn who is in a feud with who, who would help who depending on what sort of help it is needed. Amazing what sort of patterns and habits you can learn by listening to gossip.