An excellent essay by William Neil on how thinking in themes will lead to a stronger portfolio.
"If you ask a photographer what kind of images he or she makes, the answer most commonly refers to a list of divergent subjects. Over the years, I have seen evidence of the camera’s seductive power in student work. Most of us have diverse visual interests and are naturally pulled towards many subjects. This wouldn’t be anything to worry about except that a broad focus often leads to a less than optimal portfolio without focus. Certainly the world is full of wonders to photograph, but how many of us have the time to take every branch in the road? The hectic pace of our lives, and the expediency of clicking the shutter, conspires to distract us!
In my experience of teaching photography for the past twenty-five years and reviewing portfolios, I have not often seen work presented in a tightly edited and conceptual concise manner. In recent years, through the process of teaching an online course (see Final Notes below), I have found a great way to improve your photography and give it more focus – by determining the major themes within your photo library, and developing refined and concise portfolios of those themes that inspire you the most...."
Thinking in Themes - complete essay.