Now, as we discussed last time, the middle of the book is usually the hardest part to write. The first 25 - 50% being the worst of the section. Now that we're getting into the meat of the story, things get a little bit easier. From 50 to 75% is where things start to get fun and hell starts breaking loose.
Now, to start, part of this is a continuation of what you did in the first half, with rising action, and worldly and character reactions. However, a lot of what came before should be done with unless you're aiming for some unexpected twist.
Characters that we first met in the introduction should be fully fleshed out by this point, with backgrounds explained, as well as character flaws, hopes, dreams, and partially why they find themselves in such a predicament as the story suggests. Minor characters that we met later on, can have a bit of time devoted to them to help explain their impact and so that we care when something happens to them, but that should be kept to a minimum for the most part. After all, characters we're meeting this late are likely to be victim fodder or there to give us an insight into how the main characters are starting to appear to the outside world. Things akin to "Oh my, Anne said something living under the Rhododendron bushes ate her dog. I think she's going crazy."
The main focus at this point is the rising action and the escalation. It's generally about this point that the main characters start putting two and two together as things get more and more out of hand and the story almost changes to a race to reach the climax. Now, while, depending on the story, this can be fairly smooth sailing at this point compared to the first half of the book, it can also get confusing and often, things fall short of what we expected. When it happens that scenes don't seem to stretch as far as we want, it can be easy to get lost and not know what else to add. Also, escalation can become an issue when you have between several to over a dozen separate scenes to add suspense and move things along.
Pictured: One form of escalation. (Ok, break's over.)
Now, for a suggestion of how to tackle these issues. I'm going to talk about how I tackled the issues for my work for the month. Before I even started to write, I made out a list of a dozen scenes and ideas I could incorporate into the work. I then organized that list into the order I thought worked the best in terms of escalation (and there were a few that were pretty close in terms of the suspense and fear they provoke), and then had a few friends look it over and put them in the order they thought the list should go in. Now, granted, most of them were looking at the list with no idea what the characters were like and had little to go on other than the very basic ideas on the list, but most of them came out the same I had envisioned, so I'm pretty sure I got the order right.
You'll commonly find though, that things change as you write, and that tends to be a good thing. It's one thing to have a plot and pre-set events, but forcing characters along from one to the next just to jump through the hoop usually leads to characters making unbelievable choices given what we know about them and how much they're aware of the situation. (Really, is there anyone out there who hasn't watched a horror movie and screamed "Don't go in there!!" at some point?) I've found in the writing that while the order of some things are intact, some have been switched up as the story progresses more organically. It's also something to keep in mind that the story usually lends itself to suspense when done right, and it's not just an issue of "How suspenseful is this scene?" but an issue of "How suspenseful is this scene in the current context of the story?". When things take off on their own, it can occasionally happen that by the time you reach a certain scene, the suspense has already been ratcheted up so high that the scene doesn't add anything more to it. When that happens, you need to look at it objectively and ask if you can change things realistically so that it works, or whether the story is better off without it. For NaNoWriMo though, we're focused on quantity over quality, and cuts like that are made for revisions anyway, so for now, add it all in, figure out what works and what doesn't later.
Then there's the climax. The ultimate high point you've been reaching for this whole time. You have to make sure every scene escalates, and reaches for it, but that nothing eclipses it before you get there, or gives away a final plot twist. While some would include the climax at the tail end of this section, I think if your story maxes out at 75% or less, you're probably moving too quickly. Despite the graph above, the falling action and resolution shouldn't take up another 25% of your book. If things need that much explaining after the final confrontation/reveal, it's another hint that you might need to go back and take another look. That's more a topic for next time though.
In the meantime, keep writing, let Hell slowly break loose in your world, and enjoy the ride, because if you aren't enjoying it while you write it, chances are readers aren't going to enjoy it as they read it either.