Fundamentals
When searching for photos to take, I look for bright colors and bright lights. Then, the next thing I look for is a puddle or other reflecting surface, such as a window, or a wet sidewalk. Walk around the scene to see where the light is reflected best, and start shooting!
Approaches
When I'm photographing a scene using the reflection in a puddle as the major focus of the image, I find that there are several ways to approach it. The first, and probably the most obvious, is to point at the puddle and capture the reflected image. Another approach may be to include the puddle and the scene behind.
View Finding
I have been having a lot of fun playing with the perspective caused by the proximity of the iPhone camera lens to the edge of the phone. It enables one to place the viewfinder about 1/2 inch from the surface of the water for a mouse-eye view of the world. I'm fascinated by this effect. But, I'm not immune to other approaches. Sometimes a scene warrants a different angle. Maybe the puddle isn't large enough.
Focus
Then, you have things like depth of field to play with. This is the area of the focus. In some, it's fun to focus only on the reflection in the puddle, leaving the background blurry. Other times, it's best to have everything in focus. One reason I take so many photos is to be able to choose later. I can't come back and retake the shots, so best to get what you can get while you can get it.
Editing
Puddles will sometimes have things in them, that either add or detract from your composition. Autumn leaves, cigarette butts. Edit these items for some additional interest. I'm sensing another post here...
Awareness
Always remember to watch the sky. It's going to be your backdrop one way or the other. You're pointing down, but the puddle is looking up. Blue makes for a great backdrop, so be wary on cloudy days. I find I'm disappointed. Unless it's dark out.
Finis
I hope you enjoy this post, and I really hope you enjoy the post that it has inspired when i develop it further. Thanks for being a part of my creative process!