Writing a dissertation is like writing a book. To make it less overwhelming, break it down into steps. The first thing to do is create your own writing space. Pick a location that is free of distraction and has enough room for you to organize and store all of your materials. Since dissertation writing is an individual process, you're in charge of managing your time effectively.
Describe what you are setting out to do and the overall function your paper will serve. Then seek out the references that will help support and delineate your topic; organize them so they're easily accessible and keep them all in one place. Creating an outline for your paper is critical, even though you may jump from one area to another. You may find that it's easier to write your introduction after you've already written the body of the paper.
While writing your dissertation, use a journal to brainstorm and mark the thoughts, ideas, questions, productivity and problems you encounter. Daily journaling provides you with a structure that can be used to generate ideas; gradually, you can direct these entries into more concentrated aspects of your writing (see historians.org). Get a big sheet of poster board and write down all of your ideas. This helps you to visualize them; your ideas can serve as focus sentences or bullet points of your outline. If you are on a roll when writing, don't stop to worry about punctuation or sentence structure. Let your ideas flow. Dissertation writing involves many drafts and revisions; you'll have time later in the process to edit and rewrite.
Regularly have your adviser and other people read your work and discuss the process with you. Their feedback will allow you to step away from your work and gain an outside perspective. This social exchange can also serve as a welcome relief from the hours spent alone during your work. Dissertation writing becomes stressful when it feels like it's consuming you and all of your time. It's important to take care of yourself and continue with your life and relationships outside of the dissertation arena. Doing things like yoga, going for a walk, getting enough sleep and eating well can help to minimize stresses and keep both your mind and body healthy.