So before I start, I'll run through the way in which I define plot. When looking at the five W's (who, what, when, where, why), I tend to see plot as the what and the why. It's the events that take place, the actions of the characters (yes; this kind of overlaps with characterization), and the reasoning behind everything.
Things happen, and that's, essentially, the plot in its most basic definition.
Plot points are essential, and personally the individual plot points are what I tend to try and come up with first when I write: Bob goes to the store; Bob sees an old friend; Bob and friend go on a date; Bob's date goes badly. If a novel was a body, I think these plot points would be the the bones; they're the scenes in which big and important things happen.
And here's what I want to get at: those bones need joints and sinew to connect them. The plot points need to lead in to one another smoothly or else you're going to jostle your reader, and more than likely not in a good way.
Back to Bob: if I give you a scene in which Bob sees an old friend, and then immediately switch to a scene in which Bob and said friend are on a date, there's a bit of confusion and the flow is just nonexistent. That's where you have to create the filler and build on that skeleton. Bob has to actually talk to his friend and ask them out before they can actually go on a date.
See what I'm saying?
That's a really basic example, and maybe this all seems rather simple, but it's important. The plot of your novel can't be jumpy; you can't just spill something on the reader and leave them going, "Wait, what?" which is something that I've done with the last few books I've read. Don't be afraid to add a little bit more detail so that the reader can follow your characters from point A to point C without getting lost.
While I'm on the subject of detail: as a writer, you have to be the one to judge what's important for the reader to know and what can be brushed aside. I'm getting a little bit ahead of myself, here, with an example from tomorrow's review, but I'll use it anyway: the reader doesn't absolutely have to know what character or design is on your character's clothing. However, if there's a pretty important detail, like the fact that the character discovers that they can wield magic, put the reader in the moment. Putting the reader in the moment is another aspect of flow, and can also provide a major plot point that could turn rather memorable for the reader, but only if you allow it to.
Here's a test: break down your novel's plot into just the plot points. Not filler, which can include character development scenes and dialogue; just look at what happens. Write each scene down on an index card, and place them in the order you want them to go in.
Now, you've got yourself a pretty reliable road map.
The next step is to take your first two scenes and ask yourself: what needs to happen in order for the characters to get from the first, to the second? When you've got some ideas, and scenes, and dialogue, that's your filler. You're creating your flow. See how it works?
I'll give you another example, this time using The Hollow Men:
Point A: Ronnie and her partner break into a government agency to steal information
Point B: Ronnie falls out the window
I'm not even kidding when I say that's what my general outline looked like. As the reader, you'd probably be extremely curious as to how the heck Ronnie got to point B when everything seemed to be going so well in point A, right? How'd she even get to that window int he first place, and why the heck was it open? And then you've got to wonder: what happened to her partner?
That's where filler comes in and where all that detail comes in handy. Because between A and B, the reader learns not only why Ronnie has the ability to survive that fall in the first place, but also the kinds of files she and her partner are trying to steal in the first place. They learn that Ronnie and her partner aren't alone and they've got other people communicating to them, and there's a small bit of dialogue in there, too. And the reader finds out that Ronnie's partner shoots the window out, and that's how it gets opened.
See how much information that is? And it's all in a smaller scene that's between two bigger scenes. Some of that detail within the smaller scene even becomes really important in the big picture of the novel as a whole.
So try the exercise, yourself. If you're confused as to how your characters got from one place to another, try to come up with some details that you can use to fill in the blanks. Your reader can jump over a few holes in the ground, but you can't expect them to clear the Grand Canyon.