For SWN? It's my current system so this is my jam.

Quiz the hell out of your players, get them to create things for the sector and increase how invested they are in the game. Write down their answers! After the session collate all the stuff and make factions they made into actual factions. This also gets them thinking about how their character fits into the world at large. Ask relevant, leading questions. Let them know that you're going to be using the answers to expand the game,

Oh, you picked the Bounty Hunter background? Have you done much bounty hunting? Do you have a regular contact that sources you missions? Was there ever a run where something went horribly wrong and what was it? Who's the one that got away? What got you into bounty hunting? What was your opinion on the work itself?

Treat all your planets as mutable till after the first session. If a player wants a world renamed then that's a thing you can totally do.

Round it out by asking if there are any factions that people specifically want you to include in the game. An example of this is one of my players was making a Babylon reference with a Poet starship captain named Rydra, this player asked (half jokingly) if there could be a "Dead Poet's Society". I loved the reference and bam, it became a faction. It's a bohemian, subversive group.

I'm not sure what else to tell you but if you have any questions yourself, I can probably answer them. If you wanted to have a poke around, this is my group's wiki that I keep updated:
https://dl.dropboxusercontent.com/s/bjzbnz66xe2ngrk/SWN_wiki_KYGFSX_PC.html . Information on that is "in universe" knowledge, it's the player's direct experience or what they can get from news sites/space wikipedia.

I genned all the systems by "hand" with dice and then edited a random generator file from the sector generator, it was a fair bit of work but worth it for the customisation level. Quite a few of the planets are player named. I have a personal spreadsheet with all the planet tags and stuff on it.