BACK TO THE FIRST RULE
The more you read, the more you get the feel for how a story is structured. An exercise I learned in a workshop was to pick up a book you’ve read and open it to the middle. There should be a major turning point in the story. I’ve often found it to be true, no matter if the book was about 200 pages or 870 pages.
Think about your favorite books. Where are the turning points? When do they occur? Open one up and see if there is a major one in the middle. Doing this helps you to know where to put them in your own story. No wonder the first rule of writing is “read, read, read.”