One area that I have improved in is my code commenting skills.
In the past I rarely left comments.
This new skill became extremely apparent when I had to add some features to a website. I built for a client 7 months ago.
I saved a TON of time because all my code was commented so I knew exactly where I needed to edit.
Even though I was the one that built this originally, I can guarantee if those comments were not there I would have sent half the day trying to figure out what was doing what.
Bottom line, communication is everything. Even if it is with yourself.