Your thesis is perhaps the most important part of your PHD journey. Here are three suggestions to make it the best that it can be.
A successful PhD thesis will break new intellectual ground. Don't be afraid to challenge conventional theories, ideas or ideologies. It is actually expected, and your dissertation will likely be the better for it. The best PhD work opens the door for other students to explore new avenues of thinking, methodology and structure.
As there will be much independent research and self-guided study involved in your program, you will be free to draw your own conclusions. Just make sure you can back them up!!
Often you will need to challenge and alter your own opinion, or perspective on your topic to make it the best it can be. Think outside the box, and challenge yourself as you formulate your thesis, just as you seek to challenge the scholars who will eventually read and judge your work.
Of course, your final PhD dissertation will not be identical to the original outline. But your life and writing will be made easier if you have a comprehensive path laid out, and you do your best to follow it. Work closely at this stage with your adviser to make sure you lay down a sound framework within which you can place and develop your ideas.
Having a good plan may help you down the road as you inevitably encounter bouts of writer's block and periods when you feel discouraged, or overwhelmed by a particular part of you work. Go back to your plan and find a new area where you can continue working. A few days, or even weeks, working on another component of your dissertation may clear your mind. You can come back to the area that was causing you trouble, look at it with fresh eyes, and a new perspective.
It never hurts to get an outside opinion or a little helpful advice when composing your dissertation. The person reading or discussing your work does not need to be an expert in your field. Your writing and the structure of the piece should always be user friendly. Your writing should have a consistent flow, and be composed in a way that keeps your reader engaged in your work.
The most complex of mathematical models, microbiology experiments, or philosophical arguments should still be organized in such a way that one can follow your argument. Do you need advice on the specific content, position, or argument that you are presenting and defending? In that case, it's probably best to consult with your academic peers, professors, and the adviser who is supervising your work.