Again, wide-ranging knowledge of news are going to be essential here. But you don't need to restrict yourself to current affairs. Having a broad knowledge of science, health, environment, lifestyle, arts and business news will let your potential employer know that you have the ability to cover a wide variety of topics. But don't just grab for the hottest event from the past year. Try to think of something which hasn't been covered as much as you would have liked, which affects the publication's audience at the grassroots level. This will show you're an original thinker. Also, suggest how you would have spun the topic. This will tip off your potential boss that you're ripe and ready to get to work with the confidence to pitch your own ideas.