Buildings can become playful design elements in sky photography. They not only provide a subject for you to focus on, but they also add interesting shapes and textures, especially against boring (but beautiful!) clear blue skies. Courtyards can frame the sky in an unusual way, and the edge of a skyscraper against the sky can create a graphic pattern that jumps off the screen.
While exploring the city, put your phone down and keep your eyes open for subjects that you find interesting—you never know where your next bit of inspiration might come from. Once you find something that catches your eye, play with as many angles, positions and compositions you can think of. You’ll be glad you did later, when it's time to pick your favorite.