The term "substantial" indicates the dissertation thesis requires new information available only through new research, i.e., information that cannot be obtained by simply reviewing previous research. Again, the only way to identify and collect this type of information is to do a thorough literature review. Again, this is where the keys to starting a dissertation are to be found.
The best way to instruct someone on how to start a dissertation is to point out the single greatest mistake made by doctoral candidates who are unable to complete a Proposal or draft of Chapter I. Your advisor won't tell you. (S)he just says "give me your proposal and then we can discuss the rest of the project". You sit down and attempt to formulate a Statement of the Problem, and list your hypotheses. You have just made the Big Mistake.
How to Start a PhD Dissertation
You should start a dissertation project by first checking with your advisor about any special requirements. A typical dissertation follows the classic five chapter format: 1) Introduction (with all of the traditionalsubheadings); 2) Review of Literature; 3) Methodology; 4) Findings; 5) Summary/Conclusions/Implications. In addition, there are frequently Appendices (copies of instruments and permission letters, for example). There is always a References list. Many institutions impose their own rules as well, so it is always wise to check before starting a dissertation or essay, treatise, or paper of any significance. A dissertation may be written in any one of a number of formats, but currently the APA format is most popular. Some universities provide dissertation help in the form of style sheets which augment the APA format with specific features. The MLA format is still favored in some fields, such as literature.