Make it a part of your development process.
Don’t put off planning your demo. Some developers make the mistake of not thinking about their demo until they have finished with the code. Instead, consider the demo right from the beginning. Being able to easily demonstrate the change’s functionality could help guide how you will implement the story.
You may be able to write test scripts that double as demo scripts. After all, what you are demonstrating should be covered by automated tests, so there is no good reason to duplicate efforts.
It’s best to plan your demo for a story while it’s fresh in your mind before you move on to the next story. It would be best to envision how the demo will work while you are reviewing the acceptance criteria. This way, you will not have to rebuild your code or tests to accommodating something you found while creating your demo.
The demo should be the most exciting part of the effort. It should prove you have completed the story and easily display all of the requested functionality. That way, everyone involved will have a high confidence level in the new features you will deliver to the end-users.