It's probably more honest to title this musing "What makes me a writer" or "What should/am I doing to be a writer", even "...to become a published writer" (cuz inclusion in my college and high school literary magazines doesn't really count.)
As of this afternoon, here are my answers:
3) Read writing by good/great writers (and/or if I don't like the writing I'm reading, think about why.)
In supplement to these basic practices, the following seem to be helpful as well:
a) Connect with other writers
b) Critique their work, and be critiqued by them
c) Attend select writers conferences and/or programs. (I recently had a great week at Vermont College's Postgraduate Writer's Conference, and plan to attend SCBWI Michigan's event in October)
I hesitate to add d) Read books about writing, because for many many years I read writing books but didn't write. Okay, I journaled, but didn't take the next step. So, approach the reading about writing with caution.