If your story somehow fits into one of those categories, post it.
Write about things you find particularly interesting, or particularly thought-provoking. The challenge is to get other people to read and comment on your story, and perhaps post their own.
That said, we want to be sure that what we post is accurate, and that the new science we write about has been vetted by other scientists, either through publication in peer-reviewed journals or by presentation at scientific conferences. Many stories that make the newspapers are from press releases by universities just before research is published in a journal like Science or Nature. Look for those kinds of references when you're searching. Or, if the topic is kind of sketchy, use it as an opportunity to get others thinking critically about the story: how could you prove or disprove it? What sorts of evidence are researchers looking at?
Post links to your sources and additional materials.
Using some simple code, you can add links to other websites related to your story. (It's always good to include links to your sources.) This example makes a link:
I found this <a href="http://www.example.com">cool website</a> you should check it out.
Play around with the formula a bit so you can see how it works.
There is more formatting that you can apply to your posts, like making text bold, etc. Learn more about formatting.