Have you ever played chess? If you have, you know that it’s imperative to stay one or more moves ahead of your opponent in order for you to have a chance at winning the game. The same goes for the villain in your story. They must always be thinking ahead of the main character. They have to do this so they are doing their job within the story. Otherwise they won’t be believable. Villains are devious. They plot and scheme, making your main character’s life miserable. They love it when the main character is down because that’s when they have a better opportunity to take advantage of them.
To best get a hold of your villain and understand him/her, do a character analysis of them just like you would your main character. They are three dimensional characters too and come with their own set of “baggage”. What in their life infected them so? To the point they are so nasty and evil?
In this character bio also include (and most importantly) a list of ways they can stay ahead of the MC. You might not use all of your ideas. That’s ok. Work what you can into your story. If you are the kind of person that doesn’t like to think in terms of evil, don’t worry about that. It’s only fiction.