I would collaborate closely with the client to fully understand their requirements and objectives for the mobile app. For this, it would be necessary to comprehend the target market, the app's functionality, the branding, and other design preferences.

I would develop wireframes and prototypes of the app, which are simple visual representations of the app's layout and functionality, based on the requirements gathered. This would enable early feedback and iterative design improvements while also establishing the overall structure and flow of the app. 

I would focus on creating the visual elements of the app, such as icons, buttons, color schemes, typography, and other visual elements. The goal would be to create a visually appealing and cohesive interface that aligns with the client's branding and provides a seamless user experience. Moreover, I would design interactions, transitions, and navigation flows that are user-friendly and efficient, aiming to create a smooth and intuitive user experience. This would involve considering factors such as information architecture, usability, and accessibility to ensure that the app is easy to use and meets the needs of the target audience.