As in the original novels, there were different races with different characteristics. Among them, there were the Human Others ( dubbed either Magicians), Shifters and Vampires. There were also Incubus/ succubus.
For the human Others at least and the incubus/succubus, they were magic users with different abilities. The difference in hexing and battle magic is perhaps the different spell abilities selected? To that end, I was thinking ofusing some akin to the Silverbrow Humans. Silverbrow Humans are just like humans except that they could cast feather fall as a spell-like ability in exchange for having less skills. So to that end, maybe a good solution is to vary that spell-like ability.
For shifters and vampires, most players have a knee jerk reaction to playing these races. The answer is simple. You simply could not play one at level 1. And the vampire is at a whooping ECL 8. Now I have seen some solutions. The best one I seen so far was the d20 modern werewolf sourcebook I read once ( if anyone could supply me the name of the book, i would be happy to update it here). In the book, the werewolf template was basically divided into a base class. Something akin to Savage Species, the more you take in the class, the better you are at being a werewolf.
So, I think I might go along with the concept for both the werewolf and the vampire.
For the vampire, I would probably be going along with the Dhampir from the Pathfinder. The reasoning is simply that it is a bit stronger than the human race but should be able to be tweaked. For the Shifter race, i think the Shifter from the Eberron is a good match.
What about the other races? Well, the Nightwatch Universe has always been primarily a Human only world. So races like elves and dwarves are probably Shadow Creatures. Now Shadow Creatures could be benign individuals or cruel manipulators. But they are always hunted down. So players playing these race may choose to be refugees hiding from the cruel Others ( as they see it to be).
In conclusion, it seems that I may need to recreate (with minimal effort) some races for the Nightwatch Universe.