One of my major problems when writing (during Nano or any time) is focusing too much on getting my characters from point A of the plot to point B. They go here, they go there, they do this thing, they do the other thing... but all that’s happening is happenstuff. I completely forget to include setting details, characters’ thoughts and emotions, foreshadowing, and a whole host of other important elements.
If this is what’s happening to your novel, here’s a simple thing to keep in mind:
It's about the journey, not the destination.
So stop what you're doing in your story and take a step back. Set aside your story for the moment and pull up a new document. Now take a deep breath and think about your character—what he’s experiencing at this particular moment in the story. Try to describe it as if it were happening to you.
A lot of times we authors tend to look down on the story from above, able to see everything that’s going on all at the same time. Try putting yourself into the story. Your view is limited. What can you see/feel/hear/smell? What emotions are you experiencing? You have no clue what’s going to happen next; how does that make you feel? Or, conversely, you do know what’s going to happen next (or think you do); how does that make you feel? It doesn’t matter what point of view you’re writing your story from—knowing this stuff will help you create realistic reactions for your characters.
While you should keep the story's end goal in mind, don't focus too much on it while you write. Leave yourself a little slack; let your characters goof off a little and have some fun. Enjoy the trip, even if you know already it's going to be full of hardship, danger, and heartache. It's going to be a wild ride and it's going to be amazing.
So instead of rushing my characters through the high-speed car chase or the near-death run-in with the villains, I need to slow down and figure out what’s going through their minds as the rapid-fire events come crashing down on them. Maybe even drag the speed down to slow motion. Hey, it’s Nano—the more words the better.