When hiring a Xamarin App Developer, look for someone with a strong background in C# programming and experience in mobile app development. Familiarity with the Xamarin framework and its tools, such as Xamarin.Forms and Xamarin.iOS, is essential for creating cross-platform applications.
Additionally, a solid understanding of mobile UI/UX design principles will help the developer create intuitive and user-friendly applications. Experience with back-end services and APIs, as well as knowledge of version control systems like Git, can further enhance their capabilities in delivering a robust application.