Our local one started with the Auregan Dominion, fighting for it.
At one point we were given a choice to change sides. The money wasn't as good, but we were given access to Star League tech, and the chance to acquire some 'Mechs from a downed Leopard (that pissed off the Wolf Dragoons and ComStar for some reason), and we acquired some interesting (and rather irreplaceable) new Mechs.
Either way, setting up your starting point where you and your opponents are using Introtech, is a good idea. It allows people to get their feet wet while not going crazy, and if you want to give them a leg up, set them up with an opportunity to get a cache of advanced tech, be it Star League, Dragoon, or Clan (depending on the time period).