Get plenty of firearms practice. Don't attack the hero alone or in pairs. The Evil Overlord hired a million of you for a reason. Never be the first one to charge the hero. Exercise care in the abuse of oppressed peoples.
Many farm implements make effective weapons in the hands of a skilled opponent.
Dilettantism is the mark of an amateur. Familiarize yourself with the specifications for sacrificial victims, and ensure that unacceptable substitutes cannot be unexpectedly introduced into the ceremony. Avoid needless embarrassment. Practice the correct pronunciation of your deity's name in the privacy of your own room before chanting it in public. Flash cards are often helpful.