In the past several months I have given a number of talks to graduate students across the U.S. on the topic of successfully completing a dissertation. Here are some of the tips that I have shared with graduate students.
1. Know Your Area of Study. Study the research literature with a critical eye. Know what has been done in the area and speculate on what still needs to be done (this will give you ideas for research topics). Read key journals regularly.
I also encourage students to research the literature both broadly (going outside of a focused area) and deeply (tracing the research back to its early roots). This helps in defending the dissertation (and in oral comprehensive exams) - demonstrating that you have a good grasp on previous research.
2. Find a "Prototype" Article (or several). Find an article(s) that most closely resembles the design and type of research you are proposing (e.g., if you are validating a measurement instrument, find a published exemplary study validating a related scale). Follow the general structure of that research report.
3. Give Constant Attention to Your Writing. Good writing is not only critical for a successful dissertation, but it relates to success in your professional career in Psychology (or in just about any professional endeavor).