I just answered this question from a first-time book-writer in an academic Facebook group I belong to (they’d written plenty of papers etc before), and figured it might be useful to share here too.

I can’t speak for an academic book (though I have just completed my thesis full draft – whoop!) but I have written 17 novels and this is how I complete a book:

1. By not ‘fixing’ it until I’ve finished it. Re-writing the introduction or first two chapters several times will never fix the saggy middle. Once it’s all together (the bits and pieces, the patchiness regardless) then it’s time to fix it.

2. Read it to myself. More than once. Sometimes out loud. I think reading anything out loud makes it very clear what can stay, what can go, and what is missing.

3. From (2) work out what the ‘story’ (ie. not the plot) really is. The plot is what happens – the story is what’s underneath, what’s pulling us along, what helps the reader dream into the content with us. Once you know this story/narrative flow, then play around with plot – in academic terms that’s probably about clarifying introduction, maybe shifting chapters, ensuring the conclusion is threaded throughout, but not written throughout so it’s just a tedious repetition at the end.

4. Repeat (2). Probably more than once. 

5. This is definitely for fiction, but I think it works for non-fiction too, ask myself what I want the reader to FEEL, not just what I want them to know. Reading is a deeply personal, usually solitary activity, this means feeling matters. You may now want or need to repeat (3) some more.

6. Stop. Let it go. This is as good as it’s going to be. Nothing we write ever matches the dreaming we had at the start. Sometimes it’s nowhere near as good as we’d hoped, sometimes it’s surprisingly loads better, but time has moved on since that first dreaming, it’s ok that it’s not what you originally imagined. Let it be what it is. And let it go. 

7. Take a breath before you start the next one. You may not think you want to now, in the throes of this stage, but you’ll be surprised how readily you forget the agonies when you hold the first copy in your hand.

8. Pay attention to holding the first copy in your hand. Subsequent books will no doubt emerge, none of them will ever be quite as thrilling as your own First Book.