It's better to send out releases by email if you can. In any case, make sure they are out a few days before the event, so that news planners have the chance to look at them and fit them into the schedule for that day. If you have any good pictures to go with the release, send these to newspapers and magazines as JPEG image files (with emails) or transparencies (in the post).
For the performing arts, review tickets can be a worthwhile investment, so find out the name of the person who could review your work. The reviewer may not be the same person as the staff journalist, so make sure you get their name. You could make review tickets available for the first night of any performances you are holding - leave those at the box-office for collection. You can limit the number of review tickets available for each performance to help balance your box office.
If you are promoting an exhibition or other activities you could send press a personalised invitation for your launch event so they can review the work. You could invite journalists in for a sneak preview of your work or work in progress before the launch, so they can write a preview article.
It is worth noting that the traditional idea of a press night is becoming increasingly difficult. With journalists having to balance reviewing a number of different shows, you may have to be flexible with them - it depends on how much you want that review!
Phone up a day or so after the reporters should have got your release to find out whether they need anything else - but don't just ask 'Did you get my release?' as this is guaranteed to wind journalists up! Ring in the morning, and not on the weeklies' busiest 'press day', and just check briefly if they have all the details they need. Journalists are used to being phoned.
Good luck! Remember, the media want stories, and you have a good story to give. Offer it in the right way and there is absolutely no reason why you shouldn't have every chance of coverage. And if you don't succeed the first time round, just keep trying.