I'm up to 30k words on this book. I've been doing this thing for the past year where I write an outline for the book and then delete it. Having an outline means I know what I'm aiming at. But deleting it means I'm free to deviate from it whenever I want. This book is much less structured than any other book I've ever written, so the organization of detail is based more on effect and intuition than it is on story logic. So I realized today, while writing the fourth chapter, that it was going in a different direction than I'd intended and that meant that I could shuffle around some other things and the result was that I very definitively completed the first act and, at the same time, found myself with little idea of what's coming next.
The most common stumbling block for me, when writing a novel, is the first chapter. There's so much to do in that chapter. You have to establish voice, tone, theme, conflict, setting, characters, etc, and I find that if the first chapter (and, especially, the first scene) aren't correct, then I can't write the rest of the book.
But the start of the second act is also something that gives me pause, because I find that this is the place where the rules of the novel are often allowed to change. Novels become different between the first and the second acts, because in the first act the character isn't yet acting. The first act, I find, is where the character is deciding what they want, and whether or not they want it badly enough to overcome the obstacles ahead of them. Whereas the second act is the one in which they do things. And when characters start doing things, the novel can switch up the rules a bit.
Sometimes this is dramatic. For instance, in many novels--especially literary novels--new points of view will be introduced at the start of the second act. I think that's because the protagonists in these novels often don't have much to do, so a sense of expansiveness can be created by opening up the world and allowing you to see the main character from a different angle.
In many genre novels, this is where the mode of action becomes apparent. For instance, my novel Enter Title Here is, at its core, a crime novel. It's about someone who commits a tiny immoral act and has to commit more and more horrendous acts in order to avoid being punished for their crime. But that's not really apparent until the start of the second act.
In other YA novels, the second act is where the book firmly establishes itself as a thriller or a romance or an adventure novel.
Anyway, the other thing I'm trying to do is I'm trying to avoid starting each writing day with a blank page. What's worked well for me so far is to write a few paragraphs, at least, of the next chapter before I go to sleep, so I have something to work with in the morning.
In the case of this novel, Sequential Events, I walked around the block a few times and finally came up with an approach that I think will work, so now I have at least a thousand words of a sixth chapter (chapters in this book are averaging 5-7k words).