Wikinews is global in reach, and potentially local in coverage. Our understanding of what is newsworthy has to be flexible enough to encompass this. Here are some rules of thumb to help you gauge what is likely to be deemed newsworthy.
How many people does the story impact? To how many people would this story be relevant? If the answer is a few hundred or less, the story would probably not be significant enough for inclusion.
Is the story getting coverage in the mainstream media? If not, that could be because the story isn't relevant to enough people, even at the local level. Mainstream media coverage isn't always an indicator, though; sometimes, they may poorly cover a worthy story — or go into a frenzy over a story that doesn't meet our standards.
Even when covering a local story, we write it to be understood by an international audience. Local stories can provide interesting color for our international readers. But if it sounds trivial when you explain it to an international audience, maybe it is trivial.
