I will encourage the promulgation of conspiracy theories. That way, any hint of my Evil Plan will be lost in the noise.
I will not panic or over-react when the Hero seems to discover my evil plan. Especially if s/he’s a True Believer in conspiracy theories. Odds are that anything I can imagine, the Hero can imagine. Even a broken clock is correct twice a day.
Should I suspect the Hero possesses evidence of my Evil Plan, I will order my minions to covertly break in and search for, then remove, the evidence. Bursting in with guns blazing attracts attention, and has too often created vengeful Heroes. On rare occasions, it has also led authorities to join the Hero in his/her efforts.
If I must kill the Hero, I will do so in a way that does not put anyone else on my trail. No paramilitary teams, rocket-launchers, explosives, or other means inappropriate to the target. Many people are victims of common criminals.
I will not concoct a conspiracy that cannot be altered to fit circumstances. I should be able to take advantage of, or cope with, events that will affect my success. This has the added advantage of making the Hero look like a raving loony when things don’t go as predicted.
Since I’ve successfully concealed my Evil Plan to date, I will not draw attention by kidnapping or killing the associates, employees, friends, or lovers of anyone able to stop me. This goes double if they only suspect that I’m up to more evil than someone in my position should be.
If my goal is world domination, I will read the ‘Evil Overlord’ and similar lists for further tips beyond this one.