Start with the problem your project is meant to solve. Write down who will use it, what they need to do and which features are essential. Keeping the scope focused makes implementation and documentation easier to manage.
As you work, record your assumptions and decisions. Keep diagrams aligned with the actual system, and make sure the project can be set up from a fresh copy using clear instructions.
Before presenting, practice explaining how the key parts work and why you made your design choices. A project you understand is easier to demonstrate and improve.