Intriguing topic... Interest in piano lessons has steadily been decreasing throughout the 20th century. Historically, before TVs, music consoles, radios, record players, the piano was the major form of domestic entertainment, as there was always at least one family member who could play. In the 1960s, there was an electronic explosion of TVs, shows, and music consoles that competed for the entertainment venue. During this time, education also started to undergo major liberal reforms in terms of curriculum, class time, sports, after school activities, etc.; The workplace slowly began to accelerate faster and faster into the 21th century, placing a time burden on parents to reinforce music education; I could go on as there are numerous cultural changes have competed for the piano lesson initiative, both from parents, children, and the times.
Fast forward to 2010, you're now competing with the internet, cell phone/texting all day, ipods, electronic pocket games, Playstation/Wii, broken families, and worse you have some parents that are as clueless as their children. All this and more is working against you. Especially with the economy now, everybody is so overwhelmed that you have to get creative with your approach... But, there is still hope as I am an optimist! Here are some ideas.

My recommendation to increase the awareness in others in a professional, marketable, and classy way.
1. As in my practice, 75% of all growth is due to word of mouth.
2. Let your current students/parents know that you accept new students, offer flexible hours, etc.
3. Expose your students in recitals, local community, and in schools.
4. Do an "Open House," "Reception," or "Meet and Greet" with prospective parents in the area.
5. Place an add in town paper, Craigslist, church bulletins, preferably in an affluent area.
6. Advertise in concert programs. There are numerous church choirs, choruses, orchestras, ensembles, etc. that promote ads. Don't underestimate this one. You're reaching a musical audience here right after someone has attended a concert and they're charged up and eager, and want their own kids to learn piano.
7. Target communities with strong education systems and schools.
8. Partner with other musicians - violinists, woodwind, percussion, brass instructors to widen your exposure and reach.
9. Offer conveniences in terms of location, public transportation, visibility, parking.
10. Start early, send educational pamphlets to day care centers letting caretakers and parents know the value of musical education.
11. Write articles in the local newspaper about the value of music, or musical topics of interest, etc. Create exposure for yourself.
Of course, I have a soft spot for fellow musicians - I'd like to see every music teacher or musician be as successful as they can be!
... It's almost midnight, I gotta go, but Good Luck!