To optimize a mobile GUI for touch interactions:

1. Use large tap targets: Ensure buttons and interactive elements are big enough for fingers to tap accurately.

2. Simplify navigation: Limit the number of taps needed to reach a goal.

3. Use clear and concise labels: Avoid clutter and ensure text is readable.

4. Design for thumb-friendly zones: Place frequently used elements within easy reach of the thumb.

5. Use gestures and swipes: Implement intuitive gestures for navigation and actions.

6. Provide visual feedback: Use animations and effects to confirm user interactions.

7. Test for usability: Conduct user testing to identify and fix issues.

8. Follow platform guidelines: Adhere to iOS and Android design guidelines for consistency.

9. Consider finger spacing: Ensure elements are spaced to avoid accidental taps.

10. Optimize for one-handed use: Design for users who may use their device with one hand.

Additionally, consider factors like:

- Screen size and device variations

- Touch accuracy and finger size

- User behavior and expectations

- Platform-specific features and limitations

By following these guidelines, you can create a mobile GUI that is intuitive, user-friendly, and optimized for touch interactions.