So - being "professional" in the 90's also meant that your headshots were face on, maybe a little head tilt, and your shoulders were a little bit on the diagonal, but not totally. You were wearing a button down shirt (preferably in a shade of blue) and a jacket. Maybe you were on a mottled grey backdrop. It's might have been mottled forest green. If it were the 80's that would have been a painter's drop cloth. Basically everyone got the real estate agent shot. Everyone. Doctors, lawyers, hair dressers... Like I've ever gotten my hair cut by someone wearing a suit jacket? COME ON. But that was the shot that said "I am a professional. I do business."
Being professional should mean that you're good at your job, not that you own a button down shirt.
Take shots that look like you being awesome.
Katherine de Boda is a professional because she's been doing a serious practice for 14 years. She's a professional because she's good at her job. She's opening a yoga studio in Scottsdale, Arizona because she kicks ass.