The computer scientist David Parnas had a great technique for helping his students who were having trouble writing their theses. His idea was this: every chapter and paragraph in your thesis should answer a question. Start your outline with questions. For example:
Chapter 1: What is this thesis about?
p1: What is the problem tackled in this thesis?
p2: Has there been previous work done on the problem?
p3: Can the previous work be improved?
Chapter 2: How did I approach the problem?
and so on.
Then the writer started answering the questions. The final step (usually) is to change the questions into headings or remove them.
Chapter 1: What is this thesis about?
p1: What is the problem tackled in this thesis?
p2: Has there been previous work done on the problem?
p3: Can the previous work be improved?
Chapter 2: How did I approach the problem?
and so on.
Then the writer started answering the questions. The final step (usually) is to change the questions into headings or remove them.