Make him the hero of his own story
Your villain isn’t just a plot device, it’s the direct opposing force to you main character. When working on his persona or writing a scene where he appears,, don’t forget his point of view. As a character, he is fighting to achieve his goal and your main character is the way of his achievement.
If you start thinking of your vilain this way you’ll soon start to write him differently, you’ll take his goal and motivations in consideration, you’ll start to wonder why he’s doing what he’s doing. He’ll get more profound and more interesting.
Give him doubts
A villain who has no doubts joins the club of the dumb ones with a winning monologue which only results in defeat. The quickly forgotten ones. Give your villain time to doubt, question his decisions, eventually back off or come back full speed.
Not only will you give your readers hope that things won’t get too ugly for your main character but you’ll also win a great share of endeared readers who have shared the same type of dark time in their life.
Give him qualities
A villain is a character, not necessarily a monster. he is also the opposing force to you main character. he must have qualities to sustain his positions and challenge your main character. Why should you readers care about a villain that has no qualities ? Why should your readers care about a villain that is no that threatening after all ? A good way to do it ti to pick the quality that is the opposite of a villain you have no respect for. I personally do not like villain that are dumb. So I tend to craft them smart.
Give him the cool toys
What’s the interest of being a villain if there is no cool items involved ?
Those will of course vary depending on the context of your novel but If your villain does not intrigue your reader, he will fall flat and come off as a simple plot device. So, while you’re brainstorming on your story, try to think of anything really cool, something you’d like to have for yourself and give it to your villain. You’ll enjoy writing him a lot more and this will reflect on the page.
NB : I use him in the article to refer to the villain, but the exact same tips apply for a female villain