In addition to training your eye photographically, I think that genuinely understanding your dSLR and learning how to manipulate its settings is by far one of the most important steps to digest as a photographer. Having a fancy camera is inconsequential if you don’t know how to use it.
In college, one of the most confusing concepts for me to understand was Aperture. The smaller the f-stop number (f/1.4), the larger the lens opening; the larger the f-stop number (f/22), the smaller the lens opening. It all seemed backwards to me at the time but knowing the difference between each setting is significant because it’ll ultimately determines the final look of your photograph.
Sometimes seeing things rather than just reading about it is a much easier way to understanding a vague concept and this video on F-Stops and Aperture does a exceptional job in painting a much better picture of everything.