Setting goals and being clear about what you want to accomplish helps you to stay focussed and productive. Write your goals SMART and break them down into actionable steps. SMART means that goals should be Specific, Measurable, Achievable, Relevant and Time-Bound.
When setting a goal, be specific about what you want to accomplish and make sure your goals are not too big or too long-term. Don't think about the entire dissertation, but instead focus on realistic and specific goals that are important steps on the way.
After setting a goal and planing individual steps, don't forget to think about how to implement these steps. How do these fit in your working routine? Pencil them in for specific times!