Become recognized in your community. Playing in ensembles for community theater events, church organizations or competitions helps you become known for your musical capabilities. People who want to learn piano will be more likely to want to learn from you if they see you are an accomplished musician.
Create a network within your community of musicians, music teachers, churches and theater directors. Be friendly and approachable and always seek out potential piano students via word-of-mouth through your network.
Get permission to post fliers with your certifications and contact information in public posting areas such as libraries and laundry facilities. Hand out business cards to people who show interest.
Charge a reasonable fee. Many piano teachers will offer the first lesson for free. Of course, you want to make money, but when starting out it is important not to charge above the average fee within your community. Ask other local piano teachers what they charge or ask their students what they usually pay to help set your price.
Keep in contact with your students and be encouraging. Understand that many students do not want to practice as much as you did to get your certification. Nudge your students along with encouraging critiques and do not take it to heart if the student decides to quit or study under someone else.