Villains always cause me problems in my stories. Not only do they hide their identity, but they hate telling me anything about themselves.
So, when Sisters in Crime offered a class on crafting characters, villains included, I signed up. My membership in SinC and their offshoot, Guppies has been invaluable to me. If you don't belong to some kind of group of authors helping other authors, please check out the options in your genre. I also belong to RWA (Romance Writers of America) and its sub chapters, KOD (Kiss of Death) and FF&P (Fantasy, Future and Paranormal).
The day-long workshop helped me diagnose my villainous problems and have a great day with like-minded writers. I was so impressed that I wrote a post with links to other nefarious sites about villains. Click the link at the top to get there.
As always, keep writing!