My new favorite book is How to be a Villain by Neil Zawacki. It's full of helpful hints, from where to locate your evil lair to hiring minions (always get them to sign liability waivers, it's a high-risk profession and insurance is outrageous) to dealing with sidekicks and animal companions.
"In the end, the most important part of being evil is feeling good about your bad self." Positive affirmation is important for bad guys, too.
I once wrote a story where the villain was so happily bad that I couldn't kill him off, even though a bunch of other characters were trying to snuff him out. He just kept popping back up, badder than ever and totally unrepentant. It's all right to fall in love with your stories, but you shouldn't fall in love with your bad guy.
Sigh. That story will never see the light of day. But maybe my baddie should have his own story...