There are tons of things I could mention that I have learned about photography over the course of the last 10 years.  One example would be lighting and how it can dramatically affect your photos.  Another example would be post processing editing and always using the latest software. 

But I think the biggest thing for me is to take my time and really "create" the photos.  When I started out I was just taking pictures of sports teams and I had to take a lot of pictures of them to make sure I got a good picture for their order.  I mean a lot of pictures.  The thinking there was that little kids are easily distracted and might look the wrong direction rather than at me or they might blink and I would miss the shot and mess up the customer's order.  This was ok when taking those sports pictures but I got in the bad habit of doing the same thing when taking senior portraits.  I was more focused on making sure I was getting a "good" photo by taking lots of pictures rather than taking my time and really studying the light or composition.  Over the past few years I have had to retrain myself to slow down and pay attention to the details rather than just pushing the trigger and hoping for the best.  I think doing that has made me a better photographer and drastically improved the quality of my photos.