Get the main point across in the first sentence. Then stick in important details and so on, down to what’s least important.
To that end, work out what’s important about what you’re press-releasing about. What’s new, how’s it going to benefit people reading about it etc.
Keep it brief and don’t get too wordy – you don’t want editors etc to get bored and stop reading.
Make sure you’ve got contact details etc at the bottom so that you can be contacted with any questions/for images etc.
Bear in mind that it’s not unusual for press releases to be used without editing – so make sure it’s up to scratch. No typos, reads well etc – get it proofed. Basically, make it easy for the press to use it.
That all refers to a press release/news story. Not sure what you mean by ‘epilogue’ sorry. Hope it helps a bit.
EDIT: Think about who you’re writing it for too – you might not want to assume any particular knowledge on the part of your audience!