I just thought of something right now. Since there is no longer any class system, you should now plan beforehand which skills you want to focus on, with all it's skilltrees and perks and form-related trees as well...

Anyway, which trees, other than their own, would be beneficial to vampires and werewolves? Then again, you might ask yourself which skills are best for yourself. Then, do a description of how you want to play and then, you'll know which perk works best for you.

Note: If there's already a thread like that, point me out about it. If this is the wrong section, move the thread and send me a PM about where is it. Thank you.

For Vampires you could be pure or battlemage if you set it up right but definitely invest in Illusion if you are a Vampire. For Werewolf it is more simple because they focus on strength and stamina, Warriors fit werewolves best. You could mix with other skills though.

You could even go for a stealthy / thief type of Vampire with illusion magic, just... whatever you do, make sure you use illusion magic.