Meeting writers: what's the etiquette?

In 1967, humourist Paul Jennings recounted attending a literary soiree where the presence of T.S. Eliot was the main attraction. 'In this room there should be the beating of eagles' wings. All the available poets in London are here, and there are some who have come in specially from Greek islands.' As he awaits the moment when he and his wife will be introduced to Eliot, Jennings ponders - 'Soon it will be our turn. What shall I say? You have formed my soul?'

I have yet to meet a writer who may have formed my soul. But I have met a few, and the problem of what to say is always there.

For me it all started in around 1967. I liked the Roger Moore Saint TV show, probably the first adult TV I ever watched, so I was excited when my dad said we were going to meet 'the man who writes The Saint books', one of his MENSA buddies. However, this was not Leslie Charteris, a somewhat exotic fellow who had 'prospected for gold, fished for pearls, worked in a tin mine and on a rubber plantation, toured England with a carnival, and [driven] a bus.' Rather, it was a man who collected music boxes, lived near Eastbourne, and had adapted some of the TV scripts for paperback publication. As a six-year-old I had little to say under these circumstances, so moment of tongue tied embarassment for both of us ensued.

Between then and now, I've crossed paths with authors a few times. These have rarely been memorable encounters (though I was apparently the first person to ask Hal Duncan for an autograph outside of an official signing event, and I did, heroically, manage to ask Paul Cornell a non-Doctor-Who question at a round table discussion.)

What approach should one take when meeting writers? I'd like to avoid
- producing the author's complete oeuvre for signing
- asking absurdly detailed questions, such as 'on page 148 of the second volume of the Gryphiad, Volus has a poniard but in the previous chapter he had a dagger - is this a clue to the fate of Ardrad?'
- coming across as over-friendly, eg blurting out an invitation for our families to go on holiday together
- making it seem all business - 'just sign the damn book, I'm going to sell it on Amazon (but I might wait until you're dead to bump up the value.) So no need to personalise it...'

I suppose none of the folks I've mentioned are household names. I did find myself standing next to Terry Pratchett at a bar once. Now many's the time I've heard people discussing Discworld stuff that is to me completely opaque, or (worse) listened to memorised passages being declaimed with humorous intent. I am not able to participate in this kind of thing. Had I spoken to Mr Pratchett (who, being admirably generous with his time, would I'm sure have responded) back then all I could have said would have been 'Hey Terry, I read a couple of yours once, can't remember much about them - is your recent stuff any good?' So I didn't bother and concentrated on catching the barmaid's eye instead. But! Having read a recent interview in Interzone, I would have something to say to the hat-wearing fan favourite! Turns out he too admires the work of Paul Jennings, a relatively forgotten humorous writer who wrote a column in The Observer in the 1950 and 1960s. (See what I did there?) Perhaps I could have started a conversation about Jennings' poetic flights of fancy. Did he remember "How to Spiel Halma" , Resistentialism, the Submerged Log Company? How about "The Dwarfs of Birmingham"? We could have had one of those annoyingly opaque-to-non-cognoscenti conversations, maybe even declaimed memorised passages... Perhaps next time.