When planning a successful press conference, here are important steps and time lines to consider:

A month before the event:

Select a media-trained speaker who is very knowledgeable about your product or service.
Reserve the room. (Consider a date and time that isn't too early, that will not conflict with a large competitor or a lunch break (unless you provide a quality lunch replacement), and try not to plan it on the first or last day of a convention.)
Send press releases to the press well in advance so they can help publicize your event.
Promote the event to other applicable media outlets (magazines, newspapers, online press, blogs, TV, and radio).
Promote the event to local media.
Create a slide show or other visuals.
Hire a professional videographer to film the event (for B-roll footage, website use, general promotion).
Prepare and print a press kit or save an electronic press kit on a USB drive or website.

A week before the event:

Create and print handouts.
Make sure you have a compatible laptop, a compatible slide show presentation and a back-up, back-up projector lamp, connector cords, power cords, etc.
Hire people to be greeters at the event.
Order refreshments for the event (if applicable).
Set up individual interviews with reporters for after the press conference (if applicable).
Rehearse.

The day of the event:

Train your greeters.
Pass out handouts.
Have extra pens and paper available for reporters.
Turn off cell phones.
Encourage interaction.
Plant questions.
Collect business cards and/or have a newsletter sign-up sheet somewhere in the room.
Hand out press kits.
Be available for individual interviews with reporters after the event.
Edit your B-roll footage.

A day after the event:

A week after the event: