I would say that I learned that Lightroom is one of the best photographic software applications to have. Photoshop is nice, yes, but Lightoom offers efficiency and a better interface, and a faster workflow for me.
I'd say I learned that I LIKE using parabolic reflectors and grids and diffusers as KEY lights, more so than I thought I would. I'd been using umbrellas and softboxes as main lights for a long time, and have recently been learning how to light using smaller sources, which work very differently than umbrellas and softboxes.
I think in 2013 I also expanded my horizons a good deal with respect to being able to branch out into more-processed "looks", and more varied "looks". For a long,long time I have strived for what I call "a quiet eye", meaning a very natural, calm, non-exaggerated, non-theatrical "look" in almost all of my photos. I would say that the year 2013 was the year where I decided, proactively, that I would start a process of reinventing my processing approaches to be more open to different "looks", even if they might be construed as hip, trendy, or over the top by people like say d.gypsum, or whoever.
I think in 2013 I also finally learned the lesson that I shoot BETTER with LESS. I've spent years learning this lesson. I'm very fortunate that I've been able to have been in the photo game for a long time, and have had the opportunity to slowly acquire a lot of nice glass over the decades, to get to a point where I have almost anything specific that I might want, or need. But I've learned that carrying LESS means shooting BETTER, at least for me.