Let’s go ahead and start with something easy. Something that actually has to do with villains that isn’t just a mission statement. Let’s write about some resources, or sources for inspiration.
Your first and best resource for overlords is “Peter’s Overlord List”, created via suggestion from the general public poking holes in all the cliche faults of overlords. The only problems I have with the list include the fact that the genre is…mixed. One moment it will say something about shooting the hero and flying out in your escape pod, the next it will talk about swords and eating roast boar and drinking mead. In a way, it covers your overlord whether he’s medieval, modern, or sci-fi…but on the other hand it makes the whole thing a little incoherent. I also disagree with some points or some parts of some points.
Another list, the Seventy Maxims of Maximally Effective Mercenaries from Schlock Mercenary by Howard Taylor, is not technically a villain list. But it does offer good advice to anyone who would follow it. As a side note, there are not seventy maxims, at least not listed in the wiki:
Regardless of what kind of villain you’re writing, you can get in the mood with the right music. Might I recommend “When You’re Evil” by Voltaire? This is my favorite rendition of it, on YouTube, where someone has animated a little cartoon to go with it:
We all know that Mary Sues are bad (unless, I suppose, you’re a brand new writer who has yet to learn of Mary Sue). There are Mary Sue villains, too – although I cannot recommend any of the Mary Sue villain tests I’ve ever seen. While the regular Sue test is meant for heroes and, of course, heroines, I find it’s still a useful tool for villains. Especially in the case of someone who is as in love with their villain as someone who is in love with their (subsequently Mary Sue) hero. The Mary Sue test is also good for inspiration in that an anti-sue can actually be a villain. The normal kind of every-day villain. If nothing else, it’s always hilarious to run a decent villain through the Mary Sue test, especially when the score comes up negative. There are a few iterations of the test; I’ve included a link to the litmus test, and a link to a variation that’s four times as long, and perhaps a little more in-depth.
(What’s a Mary Sue? Well, the litmus test has a link near the top that explains it, but I personally enjoy this little comic which illustrates a Mary Sue so well, and rather quickly: http://www.girlgeniusonline.com/comic.php?date=20051212)
Still having trouble? Here’s a neat little villain generator. A lot of the ideas are cliche or will not fit your story but they’re enough to get you thinking and maybe you’ll run into an element you like. If nothing else, try thinking why that wouldn’t work, and that might help you find what will:
Finally, the biggest and best tool, resource, and inspiration for writing villains is just to watch villains from all mediums. Movies, books, video games, to name the biggest three. Read or watch or play through a story you already have at least once before. You probably enjoyed the villain then, but this time pay especial attention to the villain. What did he do well? What victories did he gain, and how? What did he fail at, where were his flaws showing? What were his motives, and where did they show, and how? Compare him to the overlord list, even if he’s not an overlord. Was he an effective villain? Answering that last question is easy. It shares the same answer as this question: did the heroes beat him through their own merit, rather than through a major fault of the villain?
You hopefully have found some inspiration for your villain. Make him effective.