I spent an evening walking around and shooting with my relatively new Nikon D7000 and I ended up not liking most any of the photos I took..
Let's take this one for example:
The sky was blue and vibrant when I took this shot. Why did it come out so dull?
I was shooting with aperture priority and ISO 1000 and 1600 that evening. What are some things I could have done to make this photo more vibrant?