I recommend playing some of the official campaigns first if you ' re new to DMing . They ' re full of a variety of characters good bad and in between , and not all the evil characters will be necessary to fight , some may be temporary allies . In addition to that , don ' t script a battle . Write a plot hook , then what the villain wants , his minor and major goals . CoS is a good example of that . It leaves it entirely up to the DM when or where Strahd will appear and what he will do . Just have the villain do what you think he would do in that situation based on his goals . Will he ally with the characters to achieve his goal because it works better for him or are they a roadblock that needs to be eliminated ? You won ' t know until you see what the players do . I spend the week between sessions deciding what will happen based on the previous session . I brainstorm the whole week then usually leave it up in the air until the last day because a lot of times my best ideas just pop into my head at the last minute .