High Rise is possibly his most readable. The Elements series (The Drowned World, The Crystal World, The Drought and The Wind From Nowhere) is very good, Drowned World being the best, IMO. Unlimited Dream Company is well worth reading, as is Crash. His short stories are generally excellent, and maybe the best intro: Vermilion Sands is brilliant, but the best value is the (two volume) Complete Short Stories collection.

Empire of the Sun is pretty much essential if you want to understand why he wrote the way he did; why his characters are drawn and act the way they do. There's also a short essay he did for the Guardian a few years before he died, on modernism and death, which is informative (http://www.theguardian.com/artanddesign/2006/mar/20/architec...).

Also, this site is good: http://www.ballardian.com/

From the short stories, you might start with the following:

The Thousand Dreams of Stellavista, The 60 Minute Zoom, The Secret History of World War 3, The Intensive Care Unit, The Gioconda of the Twilight Noon

The novella, Running Wild, might be a good place to start.

With his novels, I would read the big three from the 70's (Crash!, Concrete Island, High Rise), and then maybe the two best of his latter period (Cocaine Nights, Super-Cannes).

"High Rise" is accessible. It was written in 1975 so might be a bit dated.

http://www.vice.com/en_uk/read/underappreciated-masterpieces...

Short stories, then Crash, then the Atrocity Exhibition. The last is almost incomprehensible until you're familiar with his themes (and you'll still need the annotations), but Crash and AE are his crowning glories.

My favourites are his short stories. There's a "complete collection" available.