Carl Zimmer in The Loom:
First a caveat: I am probably the wrong person to ask for this advice. I stumbled into this line of work without any proper planning in the early 1990s, when journalism was a very different industry. The answer to “How do I become a science writer?” is not equivalent to “How did you become a science writer?”
I was the sort of kid who wrote stories, cartoons, and failed imitations ofWatership Down. By college, I was working on both fiction and nonfiction, majoring in English to learn from great writers while trying to avoid getting sucked into the self-annihilating maze of literary theory. After college, I spent a couple years at various jobs while writing short stories on my own, but I gradually realized I didn’t have enough in my brain yet to put on the page.
More here.