Here are a few things I've learned that have made a big difference in my printing:
For some reason, if I asked myself the question "Do I need more contrast", I used to always answer "Yes." Maybe it's an American thing, or a male thing: more has to be better than less, right? A few months back, while struggling to print a particular negative, I pulled out my never-used #1 filter. I was shocked! Suddenly I had this delicate highlight detail, and to my wife's eye (my best critic) it still had plenty of contrast. We all chase the elusive "luminostiy." I think one of the best places to find it is in well rendered highlights. These days, the #1 gets much more use.
As a corollary to the above: fiber paper (at least the Ilford that I use) takes 2-3 days to fully dry. I print so that, at the time of development, there is no detail in the brightest highlights. A couple of days later, voila.
Technical competence is crucial. But, in many of the prints that I look at, I see the same thing: they were made in unfavorable light. My best prints, almost without fail, are from negatives that were shot in beautiful light. Without good light, it's an uphill struggle.
Strangely enough, I posted this same opinion about light on a forum on ph*t*.net. It turned into a huge thread, and a huge fight, with many posters having the opinion that "there is no such thing as bad light."