I already opened a post about this (A, P, AvP Timeline). I got this timeline as far as I was able:
Predator (although is the first script made novel, before Stan Winston came and created the ultimate hunter)
Predator Concrete jungle
Predator Cold war
Predator Big game (I put it here because of the order in the literature section of this site, since it's a standalone in the present day it can be placed anytime you want)
Predator 2
Alien sv Predator Movie novelization
Aliens Steel Egg (still to read, but afraid since the author is the same of Forever Midnight...)
Alien
Aliens
Alien3
Aliens Earth Hive
Aliens Asylum
Aliens The female war
Aliens Genocide (a lot better than the comic it comes from, by the way)
Aliens Alien Harvest
Aliens Rogue
Aliens Labirinth
Aliens Berserker
Aliens Music of the spears
Alien Resurrection (novel and Junior novel)
Aliens Original Sin (a bit of screwing up Alien origins, but nice reading)
These I still have to place for obvious reasons
Predator Turnabout (still to read)
Predator South China Sea (still to buy)
Aliens DNA War (still to read)
Aliens Cauldron (still to read)
Aliens Criminal Enterprise (still to read)
Aliens No Exit (still to buy)
Forever Midnight and Flesh and Blood are out of the picture since they go against the common knowledge about predators stated in all the other books.
Quote from: Travis Touchdown on Apr 10, 2010, 07:15:09 PM
Earth Hive
Nightmare Asylum
Female War
Prey
Berserker
War
Hunter's Planet
Concrete Jungle
Cold War
These are definetly the unavoidable reading order ones, all the Alien novels after female war you can read anytime you want, but the first three cover one single big event that changed history and influenced the other books, except for Alien Resurrection which completely ignored them (one big mistake Jeunet did - among others - by my point of view and I hope Antal does not with Predators).
Thank you, Travis, for the hint about AvP novels. I never decided "when" to put them in the timeline.