I'd like to point out that although very connected, TT and 40k are two very different things. You could be a massive fan of the universe and never step into a game store. You could play TT and know only a little bit of the lore.

Something I'd suggest doing to someone who is completely unfamiliar to the universe is get into a good natured philosophical debate/discussion with someone you know and relate one of the many themes that 40k has - the pursuit of perfection from the Emperor's Children, the cool relationship between Hope and Despair of Nurgle and Tzeentch, the incredible struggle the IoM undergoes on a daily basis just to keep functioning. Sell them stories, not models and games. That's the difference between a customer and a fan.

Naaah, THIS always works .

It's what had drawn me to 40k in the first place. And when I come to think about it, that was 10 years ago.
Damn, I feel old now.

I've been trying to convert one of my good friend to the 40K universe trough TT and it is working very well, he has been asking me if we can play some TT lately and this one time when I was painting a guardsman he took a seat next to me grabbed a pencil and started painting another guardsman, I'm planing on borrowing him one of my 40K novels.
Soon he shall be one of us. * evil laughter*

I would root for books. Easiest way.

I think the hardest part about getting people into 40k, is choosing what race to "sell" them.
One of my friends is just a hardcore Monster movie fan. Loves Godzilla. Loves Alien. It seemed like Tyranids would be a good match for him.

Another one of my friends likes to play the good guys in every game. He played through Mass Effect in the most straightedge, good-guy fashion, and never really was a fan of the psychic powers or flashy stabbing. I figured if I was gonna show him 40k, I would show him the Tau.

Unfortunately, it was kinda hard to find good stuff to show my friend about Tyranids. I exhausted Lexicanum. Found some images on google. I would have showed him the Dawn of War, but the first game had no Tyranids, and when the Second Dawn of war came out, it only had a space marine campaign (until Retribution was released, and still, the Tyranid campaign was really not... well written in my opinion). There weren't any real books about Tyranids either, just Tyranids getting killed by X faction.

My other friend who was into Tau sorta had the same problem. When I got him into the universe, the first Dawn of war was old already, and the second dawn of war didn't have Tau. I didn't feel like buying an old copy of Firewarrior or anything. I suggested he read one of their books.

I myself had the same problem. I loved the Dark Eldar! Read Path of the Renegade and Path of the Incubus, then was pretty much... done.

If all three of us liked Space Marines or even the Guard, I think things would have gone easier. But... none of us could get into them.

I tell Rogue Trader and Dark Heresy stories.

Did you try with lore on genestealers ? I'm an alien fan too and genestealers stuck home for me. Their reproduction process , them infesting spacehulks , the cults they make on populated planets , how they take over slowly , the fear among the population and the hunt for them before they summon the hive fleets etc. Can't remember good short stories on them , only a few comics and a some books but the concept should be interesting to an alien fan.

My preferred method involves lots of alcohol and boreale style battle cries.
For some reason it works.

bedtime stories? We'll have millions of potential 40k fans in later years.
Veterans, start training your "neophytes" today.