I'd show them the entire season 6 and tell them to Wikipedia the previous episodes. Season 6 is the easiest season for newbies to follow. It tied everything together and was the least complicated season. Probably because it was off-book.

Begin at the beginning and go on till you come to the end; then stop.

It depends on their personality. Some might be won over by seeing Emilia Clarke in the nude in the pilot.

The first Episode FFS. I've gotten probably 20 ppl hooked on this show.

I wouldn't. That scene dragged on and was quite silly. I could see where that scene might turn someone off, thinking that the entire show is about zombies.
I would just explain that scene briefly, and have them start from after the opening credits of that episode.

I would show them the intro and the first scene of ep1 - the one with the watchers beyond the wall.

This message has been deleted.

Oh, you rated the thing a 10. That's what idiots do. I won't eplain you why, you won't understand.
Go hide somewhere.
Long may she reign
http://i.imgur.com/BxJJSJZ.jpg

An utterly stupid supposition. Get a brain.
Long may she reign
http://i.imgur.com/BxJJSJZ.jpg

^ This
I only got into the show after hearing good things and after watching the pilot I was hooked.

Winter is coming

why not just explain to them the gist of the story, and have them watch the first episode?
I personally would not get anything out of watching some random scene from a random episode in a series. I would want to watch from the very beginning, and see if it's something I would want to continue.

that fight scene with bronn and jamie and the dornish was beep because they got beep extras to play the dornies.

I'd show them any episode with Littlefinger's ever-shifting accentsthink Daaaaahk Forces, here. Oh yeah, and Dany crowdsurfing. And if that doesn't ensnare them, give them a good strong dose of Sand Snakes, especially the meticulously epic "fight" scene at Dorne with Jaime and Bronthat ought to do it.

I wouldn't show them a battle episode as they're few and far between and represent a galaxy far, far away. most of the show is not that. maybe i'd show them the episode where olly gets killed by needle at the end.
or Two Swords. Two Swords is just a beep killer of an episode.

i'd show them something early on that had an effective story-resolved-in-the-episode episode. like, the one where tyrion meets bron and has bron fight for him in the vale maybe. that's just off the top of my head i haven't given it much thought.