Join the Coalition! Save the galaxy!
The Galactic Coalition of Planets began as an alliance of independent nation-states which joined forces to present a united front against their common enemy, The New Order (of the Galactic Empire).
Much has changed since the early days (which, sadly, I missed). We've fought wars (most of which we've lost), made and lost new friends, suffered some crushing defeats; but what remains of the Coalition are those peoples and worlds whose commitment cannot be doubted. From the relatively peaceful but disorganized West, to the war-torn East, to the refugee-filled Cooperative, and the secluded Azguard; those people who still choose to call themselves "Coalition" are a people determined to die bearing that name; whether in another great war, by the hands of their gods, or perhaps only the inevitable passage of time.
We're the good guys, even though (In Character) a very few people have done a very good job of making it seem otherwise. We fight the bad guys, even if we know we're going to lose, because that's what good guys do. We would abandon a planet to save its population, lose a war fleet to save a civilian convoy, and accept the dominance of an evil Empire to prevent more bloodshed and loss.
As for what you might do . . . well that's pretty much limitless. Diplomat, politician, scientist, military commander, Jedi, random wandering do-gooder, trader . . . so on and so forth. Each of those, of course, has its own subset of things you might do.
The only other "good guys" currently around are the "Contegorian Confederation" and the New New (New?) "Alliance to Restore the Republic." You're going to want to talk to Corise Lucerne for either of those two.
Oh, well, there's the Jedi Enclave too. Talk to Zark Ekan about them.
And if you want to know more about the Coalition, ask either Dolash or me (Dolash is in charge).