Just some ideas about it, since I have been working on this subject for the last couple of days with some of my customers.
Here is some of my ideas:

1. Determining Your Information Sources. (You need something to write about and picking the right informational sources will make sure that your news blog is not only relevant but timely and unique.)

2. Find other Blogs in Your Niche (I suggest that you pay extra attention to blogs which specialize in a sub-niche because they are usually the ones who publish unique content worth mentioning.)

3. Use Social News and Bookmark Websites of Interest. (Highly recommend subscribing to the RSS feeds of active stumblers, instead of using the toolbar to stumble pages yourself.)

4. Keyword Watchlists (Monitoring of specific key phrases or keywords related to your blog in order to pick up on relevant news in a place like Google Alerts.)

5. Reader Tips (Your blog readers are great source of information. Set up a tips email account and publicize it on your site. You might not get many tips in the beginning when your site is new but this will change as your news site grows.)