I’ll second Small Gods as a good starting point. I wouldn’t worry too much about reading them in strict chronological order, although it’s probably best to read any given sub-series in order.
There are a couple of important things to realize.
-
There are several different groups of characters that interact infrequently, and each novel will usually focus on one of them. There’s the witches, the City Watch, the wizards, and Death and his supporting cast. Then there’s also a few stand-alones. Small Gods is a stand-alone with even less connection to the other groups of characters than usual, as it’s the only one (or maybe also Pyramids, can’t remember) that doesn’t take place roughly contemporaneous.
-
The first book of any given character group is not going to be up to the standard of the later ones. I’d say the witches’ first novel (Wyrd Sisters) is the smoothest transition to the higher quality of the later ones, and the Watch’s (Guards Guards) is the rockiest. Most of the cool elements of the Watch novels, specifically most of the supporting cast and the “fantasy police procedural” element, are less present in that one. I’d actually recommend starting the Watch series with Men At Arms.
Overall, I’d say my favorite series is the Watch (Guards Guards, Men At Arms, Feet of Clay, Jingo, The Fifth Elephant, Night Watch, Thud). Night Watch is hands down my favorite book of the entire series, although it requires the context of the previous novels to appreciate it fully.
The witches (Wyrd Sisters, Witches Abroad, Lords and Ladies, Maskerade, Carpe Jugulum) is probably my second favorite. After that would be the Death series (Mort, Reaper Man, Soul Music, Hogfather, Thief of Time), although I’d ignore the first two here. The Death novels are also a bit more self-contained, and Hogfather might be a nice place to start overall, since it’s essentially a Christmas story.
My least favorite series is the Rincewind novels (The Colour of Magic, The Light Fantastic, Sourcery, Eric, Interesting Times, The Last Continent). I do rather like the supporting wizard cast, who are only present in the last two. They also show up in Soul Music, Hogfather, and Lords and Ladies. I’d say to skip the first four here.
As for the stand-alones, I wouldn’t bother with any of them (except maybe Small Gods) until you’ve gotten into the setting a bit. Most of them are decent, though not outstanding. The last few (specifically The Truth, Going Postal, and Making Money) have focused a bit on fleshing out the city of Ankh-Morpork, so if you finish the Watch novels and want more of the city they’re a good place to get it.
So here’s my recommendations for places to start:
- Hogfather (one of the best, not dependent on others, and seasonal to boot)
- Men At Arms (if a mystery/cop novel in a fantasy setting sounds good, check this one out)
- Small Gods (a good introduction to the cosmology, completely self-sufficient)
- Wyrd Sisters (yay witches)