I’m pretty sure I’ve never read it either, because I don’t read many RPG rulebooks, but there are a number of good blogs and the like out there with information on this kind of thing. You could start by nosing around at:
Errant Dreams
Gnome Stew
Roleplaying Tips
Odds are, you’ll find something that’s useful to you there, even if you don’t find an answer to your original question.
My own personal advice, which you didn’t ask for, but are going to get anyway, is the following:
Your villain is not stupid (Well, unless he is, but in that case, feel free to make him a powerhouse of destruction. :P) and he’s probably not uninformed. Got a party with a mage whose favorite spell is Lightning Bolt? Well, I know which energy type the villain is going to be buffing his resistance against.
Your villain is not stupid. Why should he fight the party one on one, or AT ALL unless he thinks he can beat them? Running away is easy. Anything that makes you move faster, hides you from view, or teleports you (or makes you fly, or…) is a good get out of jail free the first time. And if you mix it up (Fly away the first time, turn invisible the next, etc) the PCs won’t necessarily have the appropriate ‘counter’ ready.
Your villain is not stupid. (Catching the theme here?) He’ll have allies and minions in the fight. In fact, allies and minions should BE the fight unless he’s sure that committing himself is what’s needed to win the day.
Your villain is not stupid. Most villains are willing to play dirty. Split the party. Hit 'em where it hurts - not just in combat, either. PCs have any NPCs they rely on? Heck, do they have any SERVICES they rely on? Are they used to being able to visit the temple and buy healing potions? Do they always hit the magic shoppe when they’re in town? Some badmouthing, rumor spreading, or straight up theft or bribes can mean that all of a sudden, the PCs aren’t getting their potions and magic items.
You are not stupid either. While it’s considered unsporting to build villains who directly counter PC strengths and have no reason to do so (Yeaaaah… he’s got a… ring of protection from gnomish hooked hammers! It’s uh… traditional where he comes from!) it’s fair game to build enemies that are strong against PC tactics and strengths that they might just reasonably be strong against. PCs favorite tactic is a melee dogpile? It’s not unreasonable that the villain might have several strong point blank AoE attacks for that sort of situation. PCs all about ranged sniping? Not unreasonable that the villain is good at closing ground or avoiding missile attacks. Now you can’t overuse this - if everyone the PCs fight just -happens- to be tailored to beat them, you’ll have crabby players on your hands in no time. But once in a while? Go for it. Just try to spread the love around - don’t make all your villains immune to flanking, or you’ll just tick off the rogue. Try one who’s immune to flanking, one with high magic resist, etc.
Pretty much every villain should have a “Get away from me!” move, where he explodes, swings his weapon around, or whatever and hits everyone who is clumped up around him to knock them back. He shouldn’t do this every round, but being able to do in a couple of times during the fight can buy him a lot of breathing room, and it’s a very movie-villain sort of thing to do anyway.
Of course, most of this is built around villains who are smart in some fashion. If you’re just building big bruisers, well, make them big and bruising and have them hit real hard, but don’t expect them to last very long when ganged up on unless you give them a significant mechanical (Read: Levels or Equivalent) advantage.