I have been making portraits with existing light for more than 45 years. Not in a studio, but on the street or wherever the person is. They are short encounters of just a few minutes.
I don't direct anything, I take the photo where the person sits or stands, at most two images. I give my business card and I am gone.
If one is interested, I will also send the photo for free in a large file. If you get a gift, being allowed to make a portrait, it is so polite to give one back.
For my black and white conversion I use analog darkroom techniques that I apply digital with Lightroom and Photoshop.
My workflow: www.straatfotografie.be