Any adventure can be broken into scenes. Each scene is characterised by a kind of action, and each scene in a role play adventure is bound to an encounter (not necessarily with something living or undead), and a location. An average session has somewhere between three and ten scenes, each lasting somewhere between 20 minutes and an hour.
A Scene: Action, Encounter, Location
So, you can have action scenes, combat scenes, chasing scenes, travelling scenes, problem-solving scenes, diplomatic scenes, spying scenes, horror scenes, role playing scenes, or even love scenes if your players dare. Actually any action you can think of could be the basis of a scene.
And then you can combine actions with encounters and locations. Like a chase scene on dragon mounts fleeing a horde of angry wyverns. Or a combat scene with a hostile city guard on the city walls. Or a horror scene with ghosts in a haunted house. Or a diplomatic negotiation with a gang of Uruks on top of a cliff. And so on.
Thinking in what kind of scene you are doing, or needing next, can help you structure your game. Are you in a slow scene? Maybe you need a fast paced action or combat scene next to keep your players awake. Have the idea your players are out of breath combat scene after combat scene, and they can't figure out your plot? Give them some breathing space with a friendly encounter in a role playing scene.
Scripting your Game in Scenes or No?
Some game masters even prefer to map out their entire game beforehand. They write out each scene before the adventure starts, at least in encounter, location, and what is to happen. With my group however that's not very useful. Typically they try to have their own agenda, and steer the adventure where they want it to go. If I try to force my set of scenes on them they just go renegade or end up frustrated – and then frustrating me.
What I often do however, is prepare a rough set of scenes – or encounters – that I can use in the adventure. Which scenes I end up using then depends on the moment, and the actions of the players. Often, the real adventure turns out quite different from what I prepared. That's part of the fun and the surprise.
Try thinking in scenes next time you run a game, while keeping start, end, enemy and stakes in mind. And see if it helps you keep grips and have more fun!