Totally new

I am a newbie too, but once you have Twilight of Arnor installed, you can launch it and play any of the three campaigns: Dread Lords (i.e., the original GalCiv II), Dark Avatar, or Twilight. For the sake of the story, after getting some experience via one or more non-campaign scenarios, I would play the Dread Lords campaign before the other two. Since you would be using the Twilight launcher, you would be playing the most updated version of Dread Lords, and any tech trees available to you would be appropriate.

hello greenchaos!

 expansions work basically the same way like in civilization, they upgrade ruleset and add new options. campaigns can be played using any ruleset, so i wouldn't bother with dl and da but start with toa straightaway.

I've been playing since near the original launch of Dread Lords and have not found the campaigns that useful for learning the game. IMO, you're better off jumping straight into sandbox mode with the base game and looking at older forum posts here (and older pages at the wiki).

Let your own learning curve decide when you switch to the 1st & 2nd expansions--both expansions add significant complexity to the game, so starting at DL will 'cut you some slack' in a sense. There's also the question of just how much satisfying game time you want per dollar you spent--if you begin at DL and play until you feel like you have it down pat, and do the same for DA, you might find the new stuff in TA all that more rewarding.

I agree with what GW is saying.  I've been playing since the original release of DL as well.  I've never played any of the campaigns all the way through.  I started a couple, got rather bored with them, then never tried one again.  I think the sandbox games are most interesting.  Since there was no option when I started playing GC2, I started with DL and have enjoyed the new features and additional complexity of the game as the expansions came out.  I would imagine starting from scratch with TA to be a bit overwhelming so I would start with DL and work my way up.  As GW says, I think you'll appreciate the additional content more that way.  As a veteran (if I may call myself that), I feel that playing TA over DA is a much bigger jump than playing DA over DL.  TA is a very interesting but highly complex game.  Definitley don't want to spoil it by getting discouraged.