My biggest problem is that I'm often at a dearth of ideas. I can target a publication or radio show or whatnot once I've got it, but I'm just not good at coming up with them. Tips?
One thing you can try (something I have just started trying), is the "fieldstone" method (cf. Weinberg on Writing: The Fieldstone Method). The analogy goes that when you are building a wall, as you walk in the field if you find a good stone, you put it in your pocket. Writing kind of works the same way: as you go about your day, you read things, you find something that interests you or bothers you, you take note of it, and over time you will see the idea for the next idea form.
One way to start coming up with creative non-fiction stories that are from your own life is by finding lists of journaling questions. For example the author of the blog Live with Flair (who was interviewed not too long ago by NPR) is posting a journaling question at the bottom of her posts daily. These questions can help you think of an event in your own life that you can spin out into a story.
Dig through old family letters. I've been amazed at the stories within my own genealogy that sound like they ought to be in a book.
For stories that are not from your own life, look at what is currently in the news. Find a story that relates - can you interview people connected with the story or who might have similar stories.
Also think of things that are currently catching your interest. Did you recently see a shooting star? Find a story within the astronomy community today. Did you recently watch an awesome sports game? Start there. Read a great book? See if the storyline of a fiction book can suggest a real-life story that might be out there.
The most important aspect for creativity is, as others have suggested here, the "raw material" that is critical to coming up with new ideas. Creativity and innovation are not a process of coming up with something completely new out of a vacuum - they occur when our brains combine two ideas together to form a third (our brains our exclusively binary operators). This can occur at any time and is usually a subconscious process that leads to those "Eureka!" moments. I scan about 800 - 1200 articles every day in my RSS reader.
So it's critical that in addition to reading A LOT, you have a collection system for your ideas. It's a mindset that I call "Always Be Collecting." Make sure you have a system in place to collect the raw materials (blog posts, pictures, new articles, presentations, etc...) and (most importantly) to record those ideas as soon as they occur to you.
It's also important to write - whether or not you have anything to say. You should be writing at least 300 words per day. It can be meaningless blather that nobody but you will ever read. If you have absolutely nothing to write about, just do a diary-like recount of your previous day with some commentary or forward-looking ideas.
I have found Google Reader to be a useful source for non-fiction story ideas.
I've created an account which is subscribed to a large number of feeds – news feeds, interesting blogs, cutting edge research feeds, and local information/events info. When I lack for inspiration, I'll go through the feeds, and through their recommendation engine, and have a long stream of fairly random potential nudges to my creativity.
You can try to use the Top-down or Bottom-up approaches:
Top-down: think about the big picture and worry about details later. For example, you can say that your story is about a lawyer that was offered a great deal of money to lose a case. Now you can refine and think about questions like: what case, how much money, why lose it etc. Those question will lead you further, and will probably help come up with new ideas and plot elements.
Bottom-up: come up with one very fine detail, and build up. For example, Mr. Abraham Jonas, a lawyer, finds an anonymous letter on his desk with the words "drop it" and a photo of his wife and children. Now, you can think about his reaction. Does he call the police? his wife? talk with his secretary and ask her who came into his office in his absence? Detailing his actions, you can then come up with more ideas, until the entire plot comes to life.
As you can see, each approach has its own pros and cons. One approach lets you think big now and work the details later, while the other lets you focus on one fine element now and worry about the bigger picture later.
The best is to combine those approaches. Think about a theme, and work the details to match that theme. But focusing on one approach is probably easier.