To ensure a GUI is both functional and aesthetically pleasing, follow these steps:

1. Define the user experience goals and requirements.

2. Conduct user research to understand user needs and preferences.

3. Create wireframes and prototypes to visualize functionality.

4. Develop a visual design concept that aligns with the brand identity.

5. Test and refine the design with user feedback.

6. Ensure consistency in design elements, typography, and color schemes.

7. Balance functionality with aesthetics, avoiding clutter and visual overload.

8. Use design principles like contrast, alignment, and hierarchy.

9. Conduct usability testing and gather feedback.

10. Iterate and refine the design based on feedback and testing results.

11. Consider accessibility and inclusivity guidelines.

12. Use high-quality visual assets, icons, and graphics.

13. Ensure responsive design for various devices and screen sizes.

14. Test for performance, load times, and responsiveness.

15. Continuously gather user feedback and refine the design.

By following this process, you can create a GUI that is both functional and aesthetically pleasing, providing a positive user experience.