I talk about module/adventure writers not explaining to the GM what's going on up-front.

I talk about thinking of your campaign as a serial.

I talk about adapting a campaign world or supplement to the ruleset you're using.

I talk about the lethality of your game, when to kill PCs and how to gauge what the PCs can handle.

I talk about moving the PCs between sessions.

I talk about the importance of foreshadowing in campaigns.

I talk about mixing two or more modules or original adventures.

I talk about how GMs should have a large campaign arc but focus on the small adventures.

I talk about having street gangs in your cities and other possible guild hi-jinks.

I talk about PC kits and alternate pieces of equipment.