Where to start?

[vampire dude]

Hi, ive been looking at writing some fan fiction for 40k (i like writing, i like 40k, it makes sense to me to combine it ) but i dont really know where to look for inspiration/making sure its factually accurate etc. How do you guys go about it? Thanks.
P.S., sorry if this is in the wrong place, it seemed to make sense to put it here.

[Eetion]

Well I usually look at my army and commander and write an in depth background and go from there.
My background for 'Cabal of the Radiant Dawn' should be around here somewhere if you want to see what I mean

This started off as a background piece for my new Tzeentch warband.

[Skits]

For information, either http://warhammer40k.wikia.com or http://wh40k.lexicanum.com/wiki/Main_Page#.T4BksPv9NBk are usually pretty good sources. Though I wouldn't stress too much about the nitpicky details to start with - 40K is a big universe, just about anything could happen. Get the story out first, then you can fix up any inaccuracies later.

As for inspiration... I suppose it depends on what you want to write about, hehehe. Personally, I get my inspiration from my own army, the backstory I have for it, and the battles I have with my friends. The story I'm currently writing came entirely from the question, "why WOULD Grey Knights and Imperial Guard team up with Thousand Sons... and then not immediately turn on them afterwards?" Bouncing ideas off your friends is always good fun, and can usually end up with things you never would've thought of yourself.

You can also get inspiration (and information!) from all the 40K novels that Black Library's already put out.

[kurisawa]

Skits and Eetion's comments seconded.

Looking to the Black Library books and all those little pieces of colour text in the rulebook and codices can provide endless inspiration, as can actual battles you play. For example, in the 5th Ed SM codex an entry amongst the battles of the Ultramarines has "Three dozen scouts under the expert direction of Veteran Sergeant Telion put down a rebellion in a single day."

That looks like an interesting story to tell. There are many more...

K.