new tip that pertains to the God Squad(priest horde). If your god squad overtakes your crusading armies for whatever reason. Try this:

Dump a spy in enemy non catholic city.
Destroy the temples with assasins. (NB sabotage is a cakewalk compared to assasination if you get the spy in successfully)
Drop the god squad in that territory.

A side effect of building lots of spies and assasins is the agent bonus.

My god squad can currently do nearly 30% per turn. In 2 or 3 turns the populace is crying out to be liberated by my good Christain soldiers.

Onward christain soldiers.
Marching out to war.
With the cross of jesus marching out before.