*Stands on Soapbox* Right then. Well, Discworld is essentially 30 or so novels, all about 350 pages. They all take place on...well, Discworld. Quite a few are loosely connected to each other, but that doesn't mean you can't just pick up one at random. It's quite a bit like Hitchhiker's Guide, except it's fantasy novel cliches in substitution of scifi. There's a bit of philosophy in them, especailly regarding tmy favorite character, Death. There are four, maybe five, subseries in the discworld. That means, essentially, that those books are related to each other, but not necessarily to the others. Vimes books, which involve the city watch, are the most common, and also the most interconnected to the other series, so it's best to either start with them or start them as soon as the word Watch appears in the text, capitals as shown. The books are frequently hilarious, very fast paced, and easy to just pick up and get sucked into. The characters are very believable and funny, but more importantly, they are distinctly different from each other.
Now then, there are q few books of the series that are very good ones to start with, as they don't depend on other books as much and if they are, the previous book's events are summed up. These books follow, with the main character and other nifty stuff in paranthesis.
Guards! Guards! (this book introduces Vimes, and is essentially a lot of action movies (they parody Dirty Harry at one point). Vimes is one of the more pivotal and human characters in all the books, so it's very easy to read the ones with him in it. He's one of the more dynamic characters, and also one of the very best. Very amusing, Start of all plots involving the Watch (in caps, of course))
Reaper Man (This book stars Death, who is very very nice and sweet. Really. this one is probably one of the more emotional ones, as it features Death being mortal. Very very good, lots of funny bits about wizards, one of which was supposed to be dead, but due to Death being turned mortal, that hasn't happened)
Soul Music (Another one staring Death, as well as his granddaughter, Susan (summed up in the begining, trust me). This one is a great parody of music, rock especially.)
Wyrd Sisters (A parody of Macbeth, introduces the Witches as main characters.)
Er, those are the basics, really. *Gets off soapbox*