In typing each person, I look at the following: behaviour, speech patterns and tone of voice, appearance, facial expressions, body language, posture, how they relate and react to others, how people speak about them, how they comport themselves in front of crowds versus one-on-one, how I feel about them personally, what they think is funny, if they exhibit any type-specific trends or remind me of anyone, and the content and expression of their words. I consider all of the above in terms of I/E, S/N, T/F, P/J. I occasionally consider Fe vs. Fi, but otherwise I tend to leave functions alone. I do look at Hogwarts House (see next post), but more for characters, I think, than for people.
Things that make typing difficult are, for one, age. If the person is very young they may not have developed enough. Often ENs, especially, appear very introverted until their twenties or later. On the other hand, if they’re too mature, people can develop their 3rd and 4th functions too much to easily tell what their 1st and 2nd were anymore – basically they become too awesome for boxes. Vocal tone changes with age, as do many other physical cues.
Occasionally people with media training (politicians and some actors, musicians, athletes, etc.) can be difficult because they’re giving canned answers to questions and they’ve been coached in how to act on camera (again, beefed up 3rd and 4th functions). It’s easier if you can catch them off-guard with something they have to think about.
People who work in fields you wouldn’t expect are tricky (say an ESFP in astrophysics, or an INTJ running a preschool) because they probably also have unusually well developed 3rd and 4th functions and it’s hard to find other people to compare them to.
Things I have tried that I have failed at miserably are typing from writing (I often only get S or N right when I later watch video of the author), typing a person from their biography alone (especially written, but also if there is not actually much video footage of that person or they’re not saying anything useful), and trying to type people from other cultures or languages where I can’t tell if the speech patterns, behaviours, etc. are cultural or personality-related. Poor video quality is extremely difficult to type from as well, since you can lose a lot of facial expression and even body language, if there aren’t enough frames per second.
I type mostly tv and movie stars because there is easy access to multiple sources of video footage of them in multiple different situations and I usually have some familiarity with them from whatever work they’ve done (yes I have watched a lot of tv). Watching interviews of them is interesting as they’re often charismatic – or if not, that is interesting too. I like that it adds another element to the story I’m enjoying (or not enjoying as the case may be).
I’ll leave this post open for comments or questions if you have them.