There are several guides to the Discworld books. Given the size and complexity of the universe, there are certainly multiple opinions on what order to read them in. I equate it to the Liaden Universe where almost no one reads the first two chronological books first, but loops back later to them. One list that made some sense to me was posted by John Chew at:
http://www.poslarchive.com/math/misc/discworld.html. His take (and I've seen it repeated from a wide variety of sources) is to avoid the first two books until after you've gotten well into Discworld. For this reason, I proposed Watch!Watch! as the first.
Spoiler:
http://<a href="http://www.poslarchi...world.html</a>
For Readers Who Understand That The Watch Books Really Are The Best
The Watch books:
- Guards! Guards!
- Men At Arms
- Feet of Clay
- Jingo
- The Fifth Elephant
- Night Watch
Before you read
Night Watch, you need to have read the other
Monks of History books:
And before you can read
Thief of Time, you have to read the
main Death books:
- Mort
- Reaper Man
- Soul Music
- Hogfather
After you've read all of the above, you probably will enjoy some of the
Witches of Lancre books:
- Equal Rites
- Wyrd Sisters
- Witches Abroad
- Lords and Ladies
- Maskerade
- Carpe Jugulum
And some of the books that stand on their own:
- Pyramids
- Moving Pictures
- The Truth
- The Amazing Maurice and his Educated Rodents
After which for completeness' sake you might as well read the
Rincewind/Cohen books:
- The Colour of Magic
- The Light Fantastic
- Sourcery
- Eric
- Interesting Times
- The Last Continent
- The Last Hero
Another, graphical, take on order:
http://io9.com/how-to-read-terry-pra...e-h-1567312812