While my first article advised against game masters having too concrete of a plan, it's equally disastrous to go in without any sort of preparation. Certain roleplaying game systems, primarily storytelling
ones, are entirely reliant on improvisation and written as such. But more
traditional systems are written under the assumption that you have larger
plan in mind. Even the best game masters are going to need something planned,
as the players are likely to notice if they’re just making it up as they go
along. Outside of systems and games where that’s the point, that level of
improvisation will sink any hope of building an in-depth or serious narrative.
The question is, what should your plan look like?
First off have it at least partially written down. It’s easy
to forget your ideas in between managing the players and shuffling books
around. However, these notes should look more like a power point than a movie script.
Make quick summaries of important characters' appearances and personalities.
Resist the urge to write down specific lines for them, as the players will
likely notice the difference between scripted dialogue and off the cuff
responses.