Step 1: Exposure
Expose for the highlights when you shoot. Avoid underexposing the darker areas too much as they will have noise issues. Find a balance between the loss of detail in the highlights and the shadows. Fix the darker areas in the image easily with an app in the editing stage.
Step 2: ISO
On an iPhone, use the ProCamera app to shoot in ISO Priority. The ProCamera app has an ISO range of ISO 25-2,000.
Use Android’s Pro Mode to alter the ISO. The range of ISO values available varies between devices, but you can expect at least ISO 100-800.
Step 3: Shutter speed
For rapid-fire shooting, experiment with the camera’s continuous shooting mode or burst mode. Play with overlaying the sequence of frames into a single image for dramatic effect.
For long exposures of light trails and moving water, use an iOS app like SlowShutterCam or Android’s Pro Mode.
Step 4: Depth of field
Add depth-of-field and lens-blur effects with an app like Focos for iOS. In both Android and iOS, play with subtle and realistic blur and bokeh effects at the editing stage with Snapseed. Add-on lenses can change depth of field, but will impact image quality.