Anatomy of an Action Scene
As we've already confessed, you are not going to remember GM tips at the table, in the heat of the moment. Things happen fast during a game, and it will come down to your personality and instincts (your GM reflexes) not pages of advice you read somewhere.
Designing the game is another matter entirely. There you have all the time in the world, to ponder, revise, rethink and question every little thing (sometimes too much time), so you might as well put it to good work. By following good design tips ahead of time, you can make it more likely that your game will play well. That's where Anatomy of an Action Scene comes in.
As a GM if you figure out your structure before a game, it helps you understand what can happen during the scene, and why the scene is happening in the first place. Armed with that knowledge you can remain relaxed during play and go along with things the players come up with. It may seem counter-intuitive, but done correctly more structure during design let's you be more flexible during play.
Here's the framework I use to describe action scenes in all the Lame Mage adventures. Not only does it help me think through the dynamic of the scene (it's step zero of playtesting), it also lays out the information very clearly for GMs running it:
1) Premise — the situation before the PCs arrive
2) Enter the Heroes — how and why the PCs become involved
3) Revelations — pivotal things the PCs find out during the scene
4) Action — what happens during the scene
5) Action Shticks — optional sub-challenges that may come up
6) Finale — what concludes the scene – there may or may not be a climactic moment, depending on the scenario
7) Aftermath — any post-action wrap-up or consequences
I write down each section header and then fill in the blanks. If you can't think of what to put in a section (for example, Enter the Heroes), than you need to take another look at how the scene is going to work in play — you may be overlooking something.
I created this framework for superhero adventures, but it works for any genre where the PCs are responding to or entering a situation (a very broad condition). You could literally define each room or encounter of a dungeon as an “action scene” and follow this same structure. Likewise, action does not have to be action per se – a fancy dinner party or an interrogation scene fit the same pattern as rescuing people from a burning building (situation/arrival/challenge/resolution).
For a good example of the Anatomy in use, take a look at Dr Null: Battle on the Bay Bridge (free download).