I intend to take our game to the planet of Gizer, known for its beautiful scenery and pale blue Gizer ale and... well that's it. Ive looked around and cant find a thing on it.

Im prepared to just create the planet from scratch of course but it seems like there should be something on it out there, somewhere?

I found what looked like a reasonable entry about it on Google but.. alas, I don't read German!

Looks like it was just mentioned in passing in a novel or two. Not terribly uncommon, really, so you can just make your own stuff up. But really...

beautiful scenery and pale blue Gizer ale

That's all I would need.

It is a start! The players are supposed to deliver something to an Alliance contact there, thought I might work up something during their stay.

One thing that may help is to find out more information about where it is located in the galaxy, and what other systems it might be near. That can help you tie it into other systems that might be better known, and help give you a more integrated feeling for the place — like it’s been there all along, you just haven’t gone over there until now.

It looks like a pretty clean slate. The most I could find was "Gizer was a planet famed for the manufacturing of the Gizer L-6 freighter and gizer ale", that it was in the Lantillian sector on the Mid Rim.

. . . .and that's it.

So yeah, go to town man. Make up whatever the hell you want!

Another thing that can help flesh out the story is to work out what industries they might have, who their enemies or competitors might be, etc….

So, why is a Gizer L-6 better than a YT-1300, but they get the shaft because everyone knows the CEC name?

If you can get to a handful of core motivations that many people on the planet are likely to share, or at least have a shared experience with, then you can start work on building a world on top of that which seems authentic.

And you may well be able to fill in the rest as you go.

I can imaging large swaths of croplands with swaying blue headed grain stalks, key to the production of the Export-Grade Gizer Ale.
Might even be some land-clearing of traditional forest creating trouble with native wildlife/greenies/old Jedi ruins/etc.

Blue ale and beautiful scenery. Maybe some mountains?

A look in the sector could provide a lot of details missing in the entry itself.

I see a lot of battles taking place on Gizar and in its system, which is good for background stories.

http://starwars.wikia.com/wiki/Lantillian_sector

You can use the adjacent systems as anchor points for history and sectorial society.

http://starwars.wikia.com/wiki/Lantillies/Legends