Re: I'm touched by the weirdness of this request...
Rafael,
Burn him! In a wicker steamroller perhaps...
I don't think there's any reading order. There are a few books which work better in sequence, but even there it really doesn't matter. It's just that some have the same characters in them, so it's nicer to come in at the beginning of their story-arc, rather than half-way through.
The one thing I would say is that you shouldn't read in chronological order. The Colour of Magic and the Light Fantastic (the only one that is a direct sequel) aren't the same as the rest of them. They're parodies of fantasy, and I'd argue they aren't as good.
He then started developing his style where he was no longer parodying fantasy. He was using fantasy to parody reality. So the next two, Equal Rites and Mort were completely different. But I don't think they're as good, because he was still developing his craft.
I would personally start with Wyrd Sisters. It's sort of a Shakespeare parody, but there are jokes within jokes. And it has the witches, who are some of the fans' favourite characters. Although they first turn up in Equal Rites (about a witch going to an all-male wizard university). But I wouldn't start there.
Or for a different theme start with the City Watch in Guards! Guards! And meet another group of favourite characters. If you like them you can then read along with their books, then start picking up others. Or just accept you like him, and go back and read from the beginning.
As a final point, you could also start with his later stuff. When he was at his peak. In which case, start with a new character with Wee Free Men - which was marketed as a childrens book in the sequence, but I really enjoyed as a 40-year-old.
Or maybe The Truth. He worked for a local paper, and so has some fun satirising it. It's more standalone, but at a period when he was turning out lots of his best books.
I found this list of his Discworld books by theme and in order, which may help.
I wish you many hours of happy reading. And hopefully laughing.
Biting the hand that feeds IT
