While I was reading the newspost linked in the OP I, of course, thought of Death taking him and when I got to your post and the tweet I could not help to smile and tear up.

Rage on Terry.

Oh no! :-( He was one of my favourite writers. This is shocking.

- There is no justice.
- NO. THERE IS JUST ME.

There are few greater authors out there. Pretty much all of the Discworld books are classics and there's no real need to read them in order (though it can help).
I would always suggest starting with the Watch books, Guards Guards is chronologically the first but Men at Arms is one of his best books so either are a good starting point.

:(
An awesome author. I bought ever Discworld book of his I could find, but I still have a few left to go.

I remember reading that he wished to pass away with his dignity, not being totally succumbed to Alzheimers, hope he got his wish.

Fuck...Gog is the first place I heard about this, now I'm choking up reading about it online...

Read everything. I'd recommend to do it in order, but really any of the first seven Discworld novels (counting the first two as one) is a perfect point to start. If you don't start with the first two, I'd say The Wyrd Sisters or Guards ! Guards !.
Alternatively, outside the Discworld canon I'd recommend The Nome Trilogy or Good Omens (albeit co-written with Gaiman, it still reads like a Pratchett novel through and through to me).

But again, read everything. Pick up what comes along, you'll reread them to DEATH anyway and get the references you missed the first time around later.

"Guards! Guards!" isn't the first Discworld novel, but I often recommend it as one of the best places to start.

"A good bookshop is just a gentle Black Hole that knows how to read".

When Douglas Adams died, I cried my eyes out.
Shit.
Not Pratchett too...

"It's got to be exactly a million-to-one chance!"

Here Be Dragons.

I'm sad now

Although I haven't read a single one of his books, my friends were excited with his stuff. Damn... RIP.

I'm sure a lot of you will know about it already, but if you ever doubted the breadth of Pratchett's knowledge then have a read of this:
http://www.lspace.org/books/apf/
It tells you about all the in jokes and references, all the obscure little bits of knowledge that you may not even have realised were jokes. It's very enlightening. Just goes to show how clever and well read he was.

Sad news, R.I.P.

The first Discworld book is The Color of Magic, but it's not one of the best, and not indicative of the quality that the series develops. I loved it personally, but many do not recommend it as a good way to get into the series.

Small Gods is a good stand-alone novel in the Discworld universe, with only a few cameos from established characters from earlier books.

Guards Guards is the first book of the "Night Watch" sub-series, and is very good.

Then there's always the non-Discworld Good Omens which he co-authored with Neil Gaiman.