According to the Directory Journal - http://www.dirjournal.com/articles/components-of-a-press-release/ - a press release should have the following components:
- Release time
- Call to Action
- Contact Info
For the details on each component, you can check out their website.
When to Use
You typically will use a press release when you have something exciting you want to announce. Don’t use it for announcing a stop on a book tour. You want to use it for really big things like the release of a new book or signing a new contract with a publisher, etc.
This is a great way to spread the word about your exciting news. Truthfully, most media outlets will ignore it, but you never know when that one might decide to look further. The greatest successes can be found by accident. Put your work where accidents could happen.