It helps to have some insight into the person you're doing a portrait of. The most interesting portraits are personal and reveal an aspect of the subject's personality. You might want to start getting into the creative process from the start -- taking your own reference photos and using people you know. If you're just sorta copying what another photographer did, a lot of the creative decisions have been made for you.
At the beginning your portraits will probably seem worse because you have to train yourself in a new skill but it will pay off eventually.
Hello : ) I'm no expert on drawing portraits, but what I've experienced a lot of the face can be made unique just from differing the nose. What I like to do is honestly look at several different people before I come up with a facial structure. I usually draw characters that I've made up and recently I've been working on taking my bf's basic character sketches and turning them into a portrait that's more realistic. I know a basic rule of thumb is never draw a portrait facing forward and the angle that the face is turned at can drastically change the emotion and contrast in the piece. What I've started doing is specially look at each major part of the face. I break it down to cheeks, lips, eyes, brow line and chin. I think by either exaggerated one of these features or even drawing attention to anyone of them by shading can really make a face pop. I still have a lot to go though, you're much better at eyes than I am, recently I've learned that I've been drawing chins really large. Well I hope this helps, if you have any feedback for me let me know, I always appreciate feedback on my portraits, they're something I really enjoy drawing, mine are still missing something though.