Here would be the best place to discuss the various AVP related novels, and go over those that were good, and those that weren't even close. So far, many of the novels were good, however the latest Predator novel, Predator: Forever Midnight, has deviated from continuity on a large scale. I've gotten through about half of the book so far, and there are a number of things that're complete changes about the Predators and how things were done. I'll give a list of things that were changed that I've observed so far.
1. The Yautja, the name of the Predators that has been used in previous novels and comics was changed completely the Hish.
2. Humans were reffered to as Ooman in all previous novels regarding the Predator and AVP series, however in Forever Midnight humans are merely reffered to as Tall Monkeys.
3. The Yautja in previous novels were stated as having different sexes, like Male and Female, and that the Female Yautja were the true power of their species as they were bigger, stronger, and in every way greater than their Male counterparts. In Forever Midnight, the Predators are made out to be Hermaphrodites, changing from male to female depending on their reproductive cycles.
4. The Predators in previous novels always had names for the worlds they visited either for hunting, training, etc. In Forever Midnight, the Predators reffered to the planet only as Saffari Planet 3998, something that's never been noted before and seems quite out of character for them. Humans give planets numbers, not the Predators.
5. The Predators in previous novels were not noted as stealing technology from other races and actualy had laws and restrictions when approaching other intelligent species. In Forever Midnight, the Preds actively had two other alien creatures on their ship that were intelligent and worked as slaves, develouping tech to be used by the Predators, one such device being a mental-probe of sorts that allows the Predators to scan a persons memories and even brainwash them.
From this I can only really gather that the Forever Midnight novel isn't canon as far as the rest of the series goes. That or these differences are only attributed to the Clan mentioned in this novel and isn't universal as far as the Predator race itself is concerned.