I write a lot about portraits here. I mention the lenses and cameras and even the lights being used but I find it more difficult to convey what rapport is and how to work at establishing rapport with your portrait subjects.
When I was younger I used to think you had to have all kinds of lines and jokes to use in a session. I thought you needed to sound incredibly smart and look like you have it together every second of the shoot. The typical stereotype of a professional photographer by aspiring photographers.
The reality is that connecting on a human level is much more important than getting every mechanical part of the shoot right. People will forgive a lot if the expression and the engagement between the model and the moment are just right. People are unforgiving of a technically excellent photograph of a despondent and disengaged subject.
In television people will forgive crappy video by they won't tolerate bad sound even for a minute. It's the same thing with portraits. A real expression is more valuable than a Profoto Air 8 power pack and a box full of heads.
I know you've heard it before but I always sit down with my subject and talk for a bit to get to know them before we shoot. I talk about how I work, ask them what they like. We do small talk and we share. How long? Could be ten minutes, could be an hour. Depends on what they have to say.
I work slowly. I talk people into poses over time. I shoot slowly. I never use continuous shutter settings. We stop and I give them (positive) feedback about how our session is going. It's always "our" session, never "my" session. If the lights are not working right I stop and tell them what's going on and how I'm going to fix it. I tell them when they look beautiful and I talk them into another pose if I see something I don't like.
I always stop to fix things that I think are important. I never presume I can fix something in post.
The session lasts as long as it needs to last. Sometimes for hours and sometimes for as little as thirty minutes...if we both know we got something great.
No phones or cellphones in the shoot. We turn them off, not down. I ask models and crew to leave theirs in the cars. I turn off the studio phone. If I have crew I like for them to be quiet and discreet during the shoot. I am trying to build a rapport and a momentary relationship between me and the subject. It's not a communal Koffee Klatch.
My goal by the end of the shoot is to have made another close friend and to have both of us want to shoot together again, soon. That all sounds so easy. It's the only hard part.