Well, the expansions do add a lot of complexity. However, you might as well just jump into the deep end, since a lot of things are streamlined in TA for new players (like, for instance, automated ship designing)

I'd suggest sandbox as well. Make sure to set the AI to truly brain dead difficulties for your first game, just so you can get a hang of the economy and such. The biggest changes introduced in the expansions are the hostile environments, spying, and multiple tech trees... so I'd play your first game using the humans (who have the most straight forward tech tree) and just ignore the hostile environments and spies for the time being. You shouldn't need them at the cakewalk difficulties anyways!

The campaign should be easier after you know how to play in sandbox mode.

Anyways, I wrote this guide to help players adjust from DA to TA, so you might want to read it. Since it seems you haven't actually played the game before, I suggest you use the guide to get a few ideas, and ask questions about other stuff.

TA 101

As for starting a game, spend points into "Economics", "Morale", and lastly "Population Growth", and use the "Federalist" party. That setup should give you a big boost to your income which should help you to do anything better. Worry about using different pre game setup once you know how to play better.

Its a matter of style and preference - personally I always go for the sandbox mode first as a way of learning the game as is.

Which ever way you go for it - learn the economy first and foremost, its the most critical part of the game (and frankly my reason for learning sandbox first). I started off playing literally only the first 12 game months or so, then restarting another game. That way I got inbto the economy and how it builds very quickly. The problem with not really getting into it fully, is you end up "firefighting" with all sorts of mayhem going on - and little time to properly learn all the other aspects of the game that you also need to learn. Take it all step by step, economy is the first step.

So learn economy first - its by far the most important aspect of the game - without it, the rest goes Bang, whatever clever tactics are employed. The best way to do that is dont build anything on planets (apart from the home world and one planet of PQ 10 or above to churn out colony ships) until population has reached the stage on each respective planet were its "in the green" in terms of income. Economy is affected by and helped a lot by economy structures etc etc - but its foundation is population, its vital to grow that as fast as you can in order that the economy can then be used to support other activities.

As to what those activities are, well, theres more suggestion on that than sand on a beach. However all such strategy and tactics are to no avail unless the economy is sound and roaring ahead. Its frustrating at first as you want to get into the whole "zap the aliens thing" - but it really is the best way to get going with this.

The classic phrase applies to this "the slow route is often the fastest route". Learn the economy and you'll quickly get to the stage of fleets wizzing everywhere etc etc, where we all want to be, try short cutting it by scimping the economy learning curve, and the game becomes the most frustrating nightmare on planet earth  

Regards
Zy

If you start playing TA, the Terran tech tree is most similar to the standard tree used in DL and DA so it should be easier to go back and play the original campaign.

The GC2 wiki has good tips to get a new player started. Most of it is written for DL or DA, but the strategies often apply to TA as well without much modification. As everyone else stated the main thing to keep in mind is to always keep growing your income. Getting a higher population (but not so high you can't keep approval up), a higher tax rate, and economy boosting buildings will all help you get enough cash to run your empire. Try to run with a surplus of income at all times.

GC2 Wiki