Reflection photography relies on reflecting the elements off different surfaces in a scene, such as metal, window glass, water, and mirrors. The magic behind the reflections in these photos is that they can turn a boring shot without anything special into an interesting photo, especially when the photographer tries to take the shot in an artistic way.
When you go outside to experience the different techniques with reflection photography, be aware of how you use the reflections in a shot, as the reflected light should be used wisely, otherwise it will spoil the final picture. For example, you need to display both the scene and its reflection wisely in the shot so people can see how the object is reflected. In some artistic ideas, you may only display the reflection itself to add a bit of mystery to the photo, and let the viewer explore and think about the reflected object and how it is reflected.
Additionally, reflections can occur on a number of different surfaces, and exploring these different surfaces can help you get more interesting shots. I agree, you have more control over choosing the reflecting surface when you are shooting indoor photos, while with outdoor scenes your options are limited to the natural reflectors you can find, such as water, lakes, and glass windows in the streets. You can also check Challenge Yourself with Photo Themes or more photography ideas.
In addition to the above, you can explore the following Gorgeous Effects and Examples of Reflection Photography and learn about the different reflection ideas and techniques.