no matter what faction i start with, i manage to earn money quickly from my neighbouring factions by offering an alliance and trade rights and demanding at least 2000 dunarii in return. They almost always agree. i did this as the Britons with the germans, the spanish, the julii, SPQR, Scipii and Brutii, and for a very short period of time the gauls before we went to war.
i earned a hell of a lot of money doing this