Coming from a print design background, I've actually had a really hard time developing effective user interfaces because I've been stuck in the "print" mindset.
Left-aligned text certainly looks good on print, but in UI design, it doesn't make sense a lot of the time. Transitioning from skeuomorphic UIs to flat UIs has been especially challenging for me because the paradigms and precedents set by the reference objects and industrial design don't exist.
One of the left-overs from print that I often find myself forgetting is that "interaction" is available as a design tool—not everything has to be visible at all times, as long as it's available in an intuitive way when needed.
Left-aligned text certainly looks good on print, but in UI design, it doesn't make sense a lot of the time. Transitioning from skeuomorphic UIs to flat UIs has been especially challenging for me because the paradigms and precedents set by the reference objects and industrial design don't exist.