Last year I made this post essentially describing what I did.
I went to a public school, APA approved, received good training, got licensed, paid my dues for 2-3 years, worked very, very hard, went into private practice, got busy, hired another, then another, then another, and another, blaw, blaw, etc. Now, I'm finally not classified as early career, but am looking at early retirement in the next 5 to 8 years. Dream big, then implement.
I have seven additional clinicians in my group. 5 therapists and 2 nurse practitioners.
To answer your question, I joined rotary and the chamber of commerce, I met with pediatricians, family doctors, dentists, OB/GYN's, lawyers, probation officers, etc. I did presentations on my services offered with job core, vocational rehab, adult protective services, child protective services, the police department, fire department, and major companies in my area. I also set up meetings with "the competition" which was essentially other mental health care providers, i.e. nurse practitioners, psychiatrists, other psychologists, and counselors. I learned about the types of patients they work well with and when to refer to them, and they learned about my practice and what I had to offer. Another thing I did is obtained a release to communicate with a patient's primray care provider and have been good about providing integrative and collaborative care. Its the standard of care, and it generates lots of business and referals from docs who had previously never heard of me.
Advertising:
My company is in the phone book in multiple locations, a 52 weeks add in the news paper, and a web site. I am looking to buy a billboard (not rent one) and then put up my companies advertisement maybe 3 to 4 months of year, then rent out the billboard space the other 8 to 9 monhts a year. I'm never without 30 to 50 business cards in my pocket and am always ready for my 30 second elevator pitch. I really love what I do and feel like I was made for this job.