How do I write a publishable press release?

Long story short, there are three main elements a publishable press release needs to respects: It has to be newsworthy, concise and easy to read and understand.

1- Catchy , Appropriate and Related headline .

2- Brief subtitle .

3- Organized , Informative , Professional Body .

4- Good conclusion

I think it all starts with the headline.
Your headline must ‘hook’ the reader (in this case the journalist or editor) into wanting to read the full release.
You should then develop a story that is newsworthy.
Make sure you have a compelling, important story to tell.
When writing your press release, you should keep in mind who the target media are and what they're looking for.
Another important rule to follow is to be honest.
Do not exaggerate, avoid flowery language, and stay away from technical jargon.
Journalists are "dishonesty" detectors, and if your story is overly embellished and sounds more like an advertisement than a press release, then forget about having your press release published.