This is the hardest part about writing: taking a big idea and generating content out of it. About 95% of the issue here is that, when writing a large section of text (like a chapter of a book), there is not enough information available that can be used as your text content body. This is where the difference between experience and inexperience come out. I've discovered though that all the minutiae, the little details that inform your chapter thesis are often put in on the second run, towards the end of the second editing run-through. All the cool ideas that you've been able to sit on and explore after the initial composition of the chapter have been able to form and settle in your mind. The result is that you have a better understanding of how you can compile the information and execute it in your chapter. Therefore, most of your little details that fill up your chapter come later, resulting in a Big-to-Small progression.
Big-to-Small is my way of saying, "take your biggest idea (top three) and lay them out sequentially in your chapter." These thoughts represent beginning, middle, and end. These big ideas will constitute an introductory "problem," or setup for your chapter.
Say I was writing a chapter about grilling. "How to Grill," would be my chapter title. What is the introductory "problem" in grilling? Why grill? I would introduce the subject of grilling as an alternative means of cooking. One grills because they want a different taste, a better steak. So my big point, A, would revolve around the problem of taste in conventional cooking, and why grilling brings something new to the table.
Point A - The problem of Taste
Our middle point is supposed to be our halfway point to the final conclusion, which is the outcome of grilling: a better taste. The middle idea could be about anything but, because taste is our biggest concern in this "chapter," I will suggest marinating as our point two. Marinating a steak changes the composition of the meat by breaking down the thickness, the consistency, and overall cooking process in grilling. It's a good midway point, and ultimately factors into taste within our grand scheme of the chapter. Your point B should always be some kind of halfway mark for the chapter.
Point A - The Problem of Taste
Point B - Marinating for better taste.
Because our chapter is all about grilling, the final end of the process should be about the actual grilling process. Again, I'm speaking hypothetically, constructing a chapter out of three points: a beginning, middle, and end. The final "act" of our chapter drives home the importance of grilling. Therefore, the "end" piece of the chapter should deal with the result of grilling, the solution of better taste from alternative cooking means.
Our three points then are as follows:
Point A - The Problem of Taste
Point B - Marinating for better taste
Point C - The "Grill"
Now that we have our three points, where do the small details come in? If you are a serious writer, after explaining these three core principals of grilling (three distinct thoughts that are easy to list, rattle off, and compose without having to strain any creativity), by now you should have encountered several offshoot topics that easily integrate into each point. Through research, outside reflection, and randoms moments of experience, you will have gained several other subtopics to write about. Each of these subpoints will constitute the connective fibers of your paper. What is the difference between smoking and grilling? (Point A) What are the effects of different marinades? (Point B) What are the flavors resulting from a good "grill?" (Point C) This is how you can go from Big-to-Small in your writing.
You can tell that I had more time to write this, huh? ;)
Hope that helps!