Doctoral dissertation is the peak of your academic career and a vital requirement for obtaining your degree. Obviously, it is the hardest mission that students have to accomplish in the course of their education, as it puts a lot of pressure on them. However, if they are persevering and stick to a set of rules, they are bound to succeed.
Firstly, you are supposed to do substantial research of the topic you have chosen. Read up on the subject and familiarise yourself with what have been done by your predecessors, as this will help you figure out the general information you need to include in your dissertation and the aspect you would like to focus on.
Once you are through with the first stage, develop a detailed outline of your dissertation, preferably with key words that will be foundation of your work and will make the process of writing easier for you. Discuss the outline with your advisor, who can highlight the weak points and give you useful recommendations how to make the structure more logical.
It is advisable to develop a schedule for writing different parts of your work and ask your supervisor to set deadlines for presenting their drafts. This will help you stay focused and avoid working by fits and starts. Try to write on a daily basis, even if you only manage to produce a few paragraphs. This will provide you with the basis to work on, as it is to make changes in the text, than to produce one from scratch. Before handing in your drafts to the advisor proofread and edit it.
On the whole, writing a doctoral dissertation is not unachievable. If you are organised and hard-working, there is nothing that can prevent you from getting your degree!