Photographer Arin Chassine has published a short article about editing photos with your phone. These are the steps he goes through:
Straighten and crop.
Adjust highlights, shadows and mid-tones.
Adjust overall exposure.
Adjust colors, but don’t exaggerate.
Go back to previous steps if necessary.
He use Adobe Lightroom for mobile. It’s free and very powerful as well as available for iPhone, iPad and Android.
Read Arin's full article at the Moment website: