Build a lair for your criminal mastermind, something that would make Goldfinger or Dr. No proud.
Must be in a hard to access location...bottom of the sea, inside a volcano, that kind of thing.
Must include deathtraps to stop pesky heroes from foiling your plans.
Must include some kind of doomsday device, so your bad guy can take over the world.
Must give your villain an emergency escape route for when the good guys close in.
Here's an example.