I'm sure that everybody is always working on improving some part of their calligraphy. We don't seem to talk about it much, though, which I think is a bit odd. Maybe people are shy. I know that as a beginner, I love to hear about things people are learning and what they're trying to improve. It reminds me that I'm not the only one.
It can be a hassle to get photos or scans of your work, though—especially if it's not something you're extremely proud of. So instead of show-and-tell, just tell us what you're working on improving (although you can post images if you'd like). Bonus points for any professionals or advanced calligraphers who share.
I'll go first:
Ascenders and the letter 'a' in Spencerian.