The first Buffy episode I ever saw was "Becoming Pt. 2" and my friends were all bawling their eyes out, and I was like, "What?" Somehow, I got into the show anyway. Part of it was that I actually liked the movie and was willing to give the series a go on that basis.

I'm one of those people who needs to watch TV in order, so I'd start with the first one. Otherwise, I might say something like "The Puppet Show," as "Hush" and "Once More With Feeling," brilliant as they are, are approximately a million times better after you're familiar with the characters.