2. The Gimmick
All right! Feeling better yet? Excellent! You're doing great, I just know! Now, you've got your name, but you need to consider one of the most important things about being a villain: your gimmick! This isn't as hard as you might think. The trick here is specialisation. Pick a skill, a combat style, a weapon, or a group of spells that you're particularly good at and play around with it. Just saying 'I'm a wizard' or 'I'm a great warrior' isn't enough anymore, because so many people are doing with it. If you want to stand out, you have to have a few tricks. Here are some thoughts.
So you cast spells? Great, that's always a good place to start. Now, narrow it down a bit. If you specialise in destructive magic, consider making most of your spells ones that involve fire, ice or lightning, or some other simple destructive force. If you're Pyroclast, Master of the Eternal Fires, let them know it with the spells you cast! You don't want to be caught flinging magic missiles or similar, do you? No! Burn 'em!
Maybe you're a warrior. There are many evil warriors out there, but the truly great one is a master of a certain fighting style. Decide on the weapon you prefer to use and get as good with it as you can, unless your hook is that you're the master of all weapons. If you want to be known for your fighting style, versatility isn't what you need to learn; master an art that involves brute force, or intelligent fighting, or agility. Explore it as far as you can.
If you're neither, then consider other skills. Maybe you're a master of disguise or a great liar. Perhaps your sharpest weapon is your tongue and you can persuade legions to your side with a word at the right time and in the right place. Make the most of it, and make the most of you.
At this point you may wish to change your name, based on your newfound gimmick. That's okay, there are no rules.