Well, I think this group has wandered around the topic. Some of these ideas like frame in camera or shoot one lens are, in my opinion, training exercises. They may help some and hinder others. I don't see these strategies as being directly connected to the goal of great photography. So, I think we got blown off course.
I have a few ideas:
1. The subject matter has to be right. There is no doubt in my mind that photographing people improves the odds, but people are by no means the only right subject matter. Think Ansel Adams for example.
2. The photographer must understand the subject matter. In the case of people this is extraordinarily complex. It is my belief some photographers are able to establish a connection with their subjects which creates an enormously positive effect on the images. This result is, IMO, not likely with professional models. I think there is something to be known about the human condition and not everybody gets it. Some of the best wildlife photos I have seen were taken by rangers and guides who are around wildlife a lot.
3. The photographer must have a sense of aesthetics. That means understanding color, proportion, perspective and who knows what else. A formal art education is not necessary, but it might help. There is more to color than avoiding a bad color cast.
4. The photographer has to be capable of creative out of the box thinking. There are dozens of rules of portraiture. A photographer who always follows then will be a decent wedding shooter, but the work will have nothing to distinguish it.
5. Obviously, one must have competent equipment and know how to use it right. Everyone around here knows my philosophy is you don't need the ultimate in gear.
6. I probably left something important off this list, but the general idea is it is about the photographer and his connection to what he shoots.