There are different kinds of publicity meant for different stages of making a movie and releasing it.
The most important is the publicity to sell the movie to the audience. This is done once the film has already been sold to a distribution company, and although that distribution company will have its own PR and marketing plan, chances are it won’t be as much as you can do on your own (or with another hired PR firm).
During this phase of publicity, you’ll want to get out there on social media (Facebook, Twitter, etc) and be featured in magazines geared towards your demographic (if you have a tattoo themed movie, for instance, you’ll want to hit up all the magazines and news outlets for ink and body modification). You’ll also want to get your movie reviewed by all the critics you can—no matter what media outlets they write for.
Please make note that it can be counterproductive to do this kind of publicity unless you have a release date. Most media outlets do not want to publish a story that isn’t newsworthy. If your film doesn’t have a release date, or hasn’t been picked up for distribution yet, it doesn’t matter to the general populace. If the public has no means to see your film, why do they want to read about it?
It could also be counterproductive because in our culture of instant gratification, when someone reads about something they are interested in, they want to click on it NOW and buy it NOW or watch it NOW. It’s one thing to build buzz for your project a few weeks from the release date, but it’s another thing to try and build it over the course of a year. People will lose interest unless you can hook them and keep them hooked.
The second most important publicity is the kind to use as a means to get distribution. This kind of marketing can sometimes overlap with marketing to the general public. But be careful. You’ll want to get some advance reviews, share news about film festival screenings and acclaim or awards won, but remember what I previously mentioned: If your film doesn’t have a release date, or hasn’t been picked up for distribution yet, it doesn’t matter to the general populace.
This kind of publicity could be more focused. For example, if your film is going to premiere at a film festival that industry buyers will be attending, you might consider compiling a list of every distribution company’s acquisitions people (names and addresses), and send postcards to alert them. Emails can get buried and lost these days. I’ve found direct mailing works wonders because most people have forgotten about it. So when they receive a sharply designed, tangible object they can hold, it’s unusual. And memorable.
If you want to hire a professional PR firm, be prepared to pay thousands of dollars. They will likely not spend as much time pushing your project as you would on your own, but they know whom to call and have relationships with the media bigwigs you don’t. Still, that doesn’t keep you from picking up the phone and introducing yourself to those same bigwigs. Remember, emails get lost or buried. It’s much more effective to call the Editor of whatever news outlet on the phone directly.
Another thing you might want to do is gather endorsements or quotes about your project from celebrities to use in your press kit. This needs to be done totally under the radar and in private. It’s a great idea to include this kind of thing in your marketing materials. It’s silly to think that people are mostly incapable of independent thought, but it’s really true. If you tell them what to think of your movie, they generally do. And if so-and-so said it was great, well, then, it must be!
Remember that famous tagline: you only have one chance to make a first impression. Premature publicity of any sort could be a disaster for your film, so when you’re about to embark on your own marketing journey, ask yourself, “is now the right time? Could we benefit from waiting a bit longer?”