Art needs an audience. The artist needs patrons. Most often, patrons need to see the audience to be patrons in the first place. A good PR firm can be the grease for the entire wheel. Or just a bunch of hot air.
As a client, I have had the opportunity to work with big firms and small, individuals and in-house employees. What I have learned is that PR is only as good as your plan. Before you hire a PR firm, have a sense of who you are, what makes your business distinct and how it all applies to your art. Without this foundation, you will get a ton of press clippings that will make for a great scrapbook and not much else.
A good PR firm can take your story to the world better than you could ever hope to. However, you still have to be your own best promoter. This means that you have to be flexible, available and creative with your PR team to give them the tools to do their job well. They will certainly have significant input, but, as always, it is your business and your vision.
I am not a fan of getting press for press' sake for any level of creative business -- start-up to major player. Unless there is something tangible that the press can provide, then it is just about ego. Even if the press is to just raise your profile, ok, so long as you are raising your profile to the right audience.
Now is the time to take a look at what you are doing to build the future of your business. Advertising, attending conferences/tradeshows, throwing/going to industry-sponsored events is certainly one way to go. Myopic to me since your audience is limited and your investment in terms of time and money is significant. Shifting that energy (and, yes, money is energy) to implementing a creative PR strategy is incredibly effective in terms of making a brand statement. The strategy may not yield immediate results in terms of booked business, but, if done well, will put your business at the forefront of what is and is going to be relevant to the audience you seek.