From an aerial photo, an above-ground pipeline appears to be a single, unified thing. And if you think of what a pipeline is all about—carrying water, oil or liquid chocolate from one place to another—that’s a single, unified process. Not unlike the story of a movie, a structure that channels and carries drama.

But look closer. The pipeline is actually a lot of smaller pieces of tube. Lengths of pipe fitted together, one after another, from beginning to end. These are like the film’s individual scenes. And as polished and memorable as individual scenes or sequences may be, they are not meant to stand alone. They need to work as chapters of the whole script. A piece of pipe only matters when it’s joined together with all the other pieces, doing their job collectively. If one scene ruptures or veers, dramatic flow is impaired and lessened. The water spills out onto the desert floor, and the city is miserably thirsty.

So a major part of the screenwriter’s job is figuring out which scenes are essential to the overall story. And that’s no small feat. At a certain stage of writing, it feels like all kinds of scenes could fit, and there’s no clear way of winnowing those choices down. Do we show the first time they meet or jump in after they already know each other? Do we need to see him get fired from his job or can we just refer to that? We shouldn’t be writing elaborate scenes for every single little beat of the story, but on the other hand, if we leave too many gaps, it will feel like something’s missing.

We also have to figure out, not just what scenes, but where they fit, where they make the most sense. Each scene should feel like it belongs exactly where you’ve put it in the script. Placement—as much as content—is essential to the effective unfolding of the story. And that’s a pretty daunting task, too.

Even experienced filmmakers futz around after the film is shot, in the editing process. Take Sideways, for example. The script is pretty close to the finished film and the director was one of the co-writers. But if you watch the movie with script in hand, you’ll find that scenes were cut from the movie. You’ll even find instances where the order of scenes was rearranged from page to screen. This is a perfectly natural part of filmmaking. Drama takes on a whole new life when the cameras start to roll, and we can’t expect to create a “change-proof” script. But we can and should make the flow of drama, from beginning to end, as seamless on paper as possible.

It’s tempting to just start writing, finessing nifty transitions from scene to scene, creating a reasonable enough illusion of dramatic flow. But what’s needed first is a coherent sense of the scenes’ place in the larger story. Lay the lengths of pipe where you think they should go before welding them together. This is where outlines come in: a picture of the overall pipeline path. If you’re writing with a reasonably complete sense of the story’s flow from one major event to the next, you’ll have clearer guideposts. And you’ll have a better sense of what you have to get to in roughly what amount of time. So begin with a chart of the film’s major events.

The next stage of your outlining will usually involve a “beat sheet,” a list of every event (beat) you envision. A beat doesn’t necessarily have to correspond to a single scene or sequence; it often does, but a beat may include numerous scenes that are part of the same general situation. For example:

The next day, Thelma starts to tell Louise about sex with JD, but Louise asks about the money: its still in the room, with JD. They race to room and the money’s gone. Louise crumples, Thelma takes charge.

Police, FBI set up camp at Thelma’s house, tapping phone.

Thelma robs convenience store. Police, FBI see it on video. Thelma, Louise feel thrill of being outlaws.

Like all outlining methods, the beat sheet is for your eyes only, so make the form work for you. It can definitely help to push your beat sheet beyond the “what” (the concrete events) and include notes to yourself about the “why” as well (the emotional motivations and significance). For example:

They race to room, discovering money gone. Louise crumples,Thelma takes charge.(Here dynamic shifts, with Thelma leading the way more and more.)

At some point, you might want to progress to a “step outline” where you actually break the beats into scenes (steps), like so:

INT. COFFEE SHOP – DAY

Thelma tells Louise about orgasm. Louise realizes JD left alone in motel room with money.

EXT. MOTEL ROOM – DAY

They race to room, discovering money gone. Louise crumples, Thelma takes charge.

If you’re like me, you’ll get tired of staring at the computer screen during the outlining process, and you’ll want to see something more tangible and physical. This is where you can break out those old-fashioned index cards. You can map out the plot of your script—beat by beat, scene by scene—on index cards, which are tacked, glued, or taped to a wall, poster-board, or bulletin-board. The beauty of index cards is that you can scribble in added details for a particular beat or scene, you can tape on new clusters of ideas around scenes, and most importantly, you can arrange and rearrange to your heart’s content.

Let the process get messy before it gets clean. Early on, your outlined script may resemble lots of little clusters of pipe-sections divided by vast expanse of desert. At some magical point, though, they all start coming together. The whole thing starts looking like that beautiful seamless tube in the aerial photo, an actual movie you could see onscreen.

But don’t let yourself sit back and admire for too long. Rather, scan/scour the whole thing over again, paying critical attention to how you feel as you move through the story. Is each scene an important battle in the script’s war? Is it an important step in the growth of an important character? Does it represent a positive or negative change? Does one scene flow into the next, in terms of action and subtext? Is that flow engaging, connecting the dots but not over-connecting or repeating them? Is momentum building?

Sometimes you won’t have the best answer until you are actually in there writing. Exploring and exploding moments. You might write a perfectly beautiful scene, but then it doesn’t seem to have a place. Or it seems to be holding up the momentum. This might mean axing it altogether. Conversely, you might start writing a scene that was supposed to be very minor, or maybe wasn’t even supposed to be there, and you find it taking on a life in a way that is absolutely central to the story. An essential gem that’s turned up in the unlikeliest of places.

That surprise discovery—when you’re right there in the middle of a scene—is one of the deepest joys of screenwriting. In the back of your mind, you’ve got that sense of overall character growth, that map of overall story arc. That’s like your safety net. And with your safety net in place, you’re free to do all kinds of stunts. You’re free to explode within the scenes, to explore between the scenes. You are free to live fully, with characters and story, in moment after moment.