At the beginning of the game I found it very useful to become allies with pretty much every other faction. Unlike after you have started a few wars - at the beginning the other states are very eager to become you ally - you can even CHARGE them for the privilege. This gives you unhindered access to all the juicy rebel states without falling out with the pope and other factions. If you are English and you want easy access to Antioch you can use this time to take Florence, a very useful base for a sea assault on Antioch when the pope calls a crusade.