Aside from the skills I recommended every serious villain should have, I want to talk about the history every serious villain should know. For those of you who are just reading my guide to see how to make money fast, skip ahead, this won't interest you. Some free advice: when you get hauled off to prison because you didn't care about investing effort in excellence, you'll have plenty of time to educate yourself in the slam. For the rest of you, tally ho!
Human history has stories about people with extraordinary powers. Saints, angels, demons, and monsters. Obviously there's a ton of interest in anthropology and archaeology and folklore, because contemporary super research could answer a lot of the questions posed by these accounts.
Siegel and Shuster wrote "The Reign of the Super-man" in 1933. Legend says that they based some of their stories on an actual guy they knew. This isn't the first confirmed superhuman, but is probably one of the most interesting, because their fictional creation was originally planned as a villain. Go us!
The "Super-man" that S&S wrote about was a guy who had powers given to him with a serum. Mythology is full of "deals with the devil" that require you to drink something, or wear something, to gain power. We know vampires are real - not necessarily the vampires of myth, but something like them. There have been Children of Lilith that strongly resemble mythical werewolves or other monsters, like Wolf 359, the Jersey Devil, and that guy in the Antarctic who calls himself "Frank".
Some researchers think that there's some sort of transition point, where the super-mutation went from something communicable to something inheritable. That's where we come in.
Most supers today gain their power in stages. The first that's on record is obviously Apollo. Everyone should know his story already, but here goes. He was a test pilot who survived the breakup of his plane in 1962. He was already one of the most physically and mentally fit guys in his unit, definitely astronaut material already, and then the crackup advances him at least to Stage 3. He got magnetism control powers and a package of secondary abilities out of the deal. In 1967, he goes to the moon without a spacesuit.
By 1970, the Wiezmann Institute in Israel has figured out the biological basis for superpowers. They have no idea how to replicate powers at all, but the signs are obvious. That's how we got terms like "Children of Eve", "Children of Lilith", and "Hashmal process", by the way.
More supers have been appearing. With nothing else to go by, many of them model their actions on the comic books that people were reading at the time. None of the "new" supers were too cautious about their identities - yet.
That changed in 1976 with United States vs. Friedel. This woman, an Eve, had eight children and sold them all. All those kids had potential for power, obviously. The FBI figured out that the people she sold them to were also kidnapping other such kids and taking them all out of the country. The whole scandal shocked the nation, and made people a lot more aware of the risks they were taking.
This meant that 1976 to 1996 was one of the worst times for villainy. Anyone who wasn't using their powers for society-approved purposes got branded as a baby-kidnapper or spy or terrorist or something. There was a big push to institute a draft of some kind. The Army ran a series of ads to recruit supers. That failed miserably, because of a simple truth: processing a kid into a soldier requires instilling discipline. The usual boot-camp regime - fear, stress, and so on - is a total loss when tried on supers. So the Army had something like a 50 to 1 ratio of dropouts to usable soldiers, and those kids who'd been put through the wringer went and worked off their accumulated resentment on the nearest city. Nobody was happy.
In 1996, the Oklahoma City bombing happened. A lot of civilian supers jumped in to try and help with the cleanup. Most of them were untrained, but even without that, the first responders did an amazing job of coordinating them.
The public loved these "heroes". And that led to the UNCLE SAM Act being passed, and signed by then President Clinton. This also led to the creation of the group ACTION. Though ACTION has been a real pain for villains, the shift of public perception was vital. Supers as a class weren't despicable and distrusted any more. We were legitimized.
Since 2002, when the All-Stars broke up and the idea of an "official government super-team" fell by the wayside, villainy has experienced a renaissance. We took our cues from the original comic-books, because people have an instinctive sympathy for pageantry. We stole from professional wrestling and they stole shamelessly from us in return. We got a lot flashier and a lot less deadly, but a lot more effective at getting what we really wanted: money, fame, and freedom.
Modern villainy owes a lot to Lucha libre, or Mexican professional wrestling. More than a few masked rudos are actual supers, and Stage 2 wrestlers compete in their own brackets. This interest spills over into the States in places where Lucha is a thing, like southern California. Because of LA's Hispanic population, a lot of showy villains play Robin Hood in the hood. There's a lot of dollars on the table for anyone who can figure out how to legitimize these spectacles.
Finally, reality television shows - as surprising as it may sound - are contributing a lot to the culture of villainy. We tune in to see ordinary people do dumb, sneaky, or spiteful things. We celebrate vice through our feelings of moral superiority at the people on the tube. We judge, but we keep watching. A lot of villains have taken to pulling "nested capers" to take advantage of this trend. They'll go for their real objective, but they'll stage (and deliberately fail at) a larger one, in which the hero is easily able to thwart them. This makes for good television (everyone likes to see the hero win), and for good villainy (several media-savvy villains are polling extremely well, and some who got captured have been granted clemency on the basis of write-in campaigns from fans).
Supervillains of Note
I'll be starting a series of biographies on supervillains you should know about. As usual, file your questions in the comments section, and I'll answer them as soon as I can!