A news bulletin is different from a newspaper page in that it has to be built on the basis of specific criteria: Is it new, unusual or interesting, significant or about people and is it current. Examining the news with these criteria in mind will help you decide which story to lead your bulletin and where to place other stories within the time available.
Choosing the lead story for your bulletin is vital; it should be important and dramatic and, as a rule, should be more recent than other stories. This is to avoid the delay between the event occurring and its reporting in a bulletin.
After that, the rest of the bulletin must be built around this and other significant events. It will often be necessary to re-order the news items within the bulletin as they occur. For example, if you start with the story of an air crash, and then get the headline that the government is resigning, it will be necessary to drop the other story.
The way a bulletin is structured will also depend on the kind of station for which it is written; a serious national broadcaster will probably want to focus on political events delivered in a serious tone whilst a youth-oriented music radio station might like to include more human interest stories (tugging the heart strings) and amusing ephemera. It is also possible to vary the structure of a bulletin between weekdays and weekends, depending on how many stories you have to work with at a particular time.