One of the biggest things for me when shooting portraits is the eyes. I learnt while working in video and cinema that selling a shot involves a lot of things, but if the eyes don't convince you, then everything can fall apart. When shooting portraits, this is something I really look for. You don't get the luxury of 24+ frames per second to tell a story. You only get one.
I am still learning how this works, and dare say that it's something that I'll never stop learning.
Above is a shot of Erin, my talented friend that has helped me so much to learn this in the shoots we have done together.