Choose the dissertation topic. Ideally the area of research you're interested in is under development already and requires further development. Come up with three or four possible approaches and consult your dissertation chair and committee members with brief notes about how approach each could work. They'll give their opinion about the workability of each idea and point out any problems that might crop up if the topics are too wide or narrow.
Study dissertation proposal guidelines regarding length (usually 20 to 45 pages) and preferred format. Format specifications may vary slightly, but will include an Introduction, Problem Statement, Conceptual Framework, Literature Review, Methodology and Bibliography. Ask to see a copy of a dissertation proposal from your research area to use as a model.
Summarize the larger issues and ambiguities that surround the topic of your proposed dissertation in the "Introduction." Locate your work within a larger research area and state your main research question. The length of the Introduction varies, depending on whether the proposal will eventually become the first chapter, or the first three chapters of your final dissertation.
State the exact issue and specific questions you will address in your dissertation in the "Problem Statement." Describe the context and background and explain why this problem or issue is significant.
Inform the reader of what is known about the subject, and what still needs to be understood in the "Literature Review" section of the proposal. Analyze and synthesize source materials, taking into account both theoretical and empirical issues. You should explain what matters about a particular piece of research and show how it supports your argument.
State the methods of data collection and analysis that you plan to use (and why) in the "Methods" section of the Dissertation Proposal. Show how this research design is linked to your Conceptual Framework.
List of all your source materials in a "Bibliography," making sure to properly format the document in whatever academic style is required.