On the train up from Dublin yesterday evening, a friend of my wife asked for hints on where to start with Terry Pratchett's Discworld novels — a daunting place to be, since, including the 'children's/young adult' (whatever that means) books, there are currently 36 Discworld books.
While any one of them could probably be read satisfactorily by itself, the series falls roughly into groups as follows (by my estimation — I think I might differ slightly from the Wikipedia page linked above):
The Rincewind books (Rincewind is a wizard of questionable talent): The Colour of Magic, The Light Fantastic, Sourcery,
Faust Eric, Interesting Times, The Last Continent, The Last Hero (I haven't read this one).
The Witches books: Equal Rites, Wyrd Sisters, Witches Abroad, Lords and Ladies, Maskerade, Carpe Jugulum.
The Death books: Mort, Reaper Man, Soul Music, Hogfather.
The City Watch books: Guards! Guards!, Men at Arms, Feet of Clay, Jingo, The Fifth Elephant, Night Watch, Thud!
The Tiffany Aching books (nominally YA books, but that's a load of rubbish): The Wee Free Men, A Hat Full of Sky, Wintersmith.
The Moist von Lipwig books: Going Postal, Making Money.
The other books all generally stand alone, although characters from the groupings above make frequent appearances. Many of these books reference the development of a particular technology on the Discworld: Pyramids, Moving Pictures, Small Gods, The Truth, Thief of Time, The Amazing Maurice and his Educated Rodents (YA), Monstrous Regiment.
That's a whole lot of books. If I were starting again, where would I start?
Not at the start. I find (and from here on in this is all my own opinion) The Colour of Magic to be one of the very weakest of the Discworld books. The author hadn't found his tone for this one: TCoM reads like it's going more for fantasy than humour, whereas from The Light Fantastic the humour takes the lead.
That probably makes it sound like these books are just a laugh with nothing serious to say. I don't think that's so, but they have become known as a humour series. The best one of the lot (Night Watch) is a serious novel that stands very well by itself, and shows the Discworld all grown up and taken seriously.
But I'm getting sidetracked.
Your best bet is to pick any of the groupings above and tackle them in order of publication (the order in which I've listed them). My favourites are the City Watch and the Witches books, preferring the City Watch by a hair. More than any of the rest these two series are all about exploring their characters.
The Rincewind novels will give you a very good grounding in how the multiverse of the Discworld works, but that's not essential for your enjoyment. They are a bit weaker, so you can wait to get to them. Moist von Lipwig's tales are good, but probably not as immediately absorbing, and the Tiffany Aching stories, while excellent, follow on best from the Witches books. Pick up the Death books whenever you like — they're a little weirder, but good.
Of the miscellaneous novels, my picks would be: Pyramids, Small Gods, The Truth and Thief of Time.
The only Discworld book I really didn't enjoy was Monstrous Regiment, but I know those who loved it.
Those are my picks. If you disagree then you know where the comment form is. If you've never read the Discworld, then get cracking!