TLDR; artstation has some learning section go give it a look.
If i had to guess cause who knows, i think figuring out a great lighting setup would work wonders for a lot of artworks even my own. I am only learning that now and boy oh boy is there a lot to learn apparently.
Besides that i think artstation is trying to help users with this very question they got some learning section, idk if that is free at all so you would have to check it out yourself i haven't taken the time to look through that but it seems some decent artworks are being promoted on that end so if it doesn't work out you can blame them for promoting that material if it doesn't work out for you when you apply it to your work.
At this 1st glance for me i see a lot of green idk about that, its not my taste and idk if that is a part of natural lighting(i am still crawling upto everyone else that seems to have the bible hidden under their beds and only shares it with a select group of people.) I heard things about browns/purples and greens, greens only for the matrix type of look, otherwise its been the other two that i have heard more of, seen more of.
From the hairs I've seen, i see them use some more faded alpha or dither blending atm the hairs do not seem to strong. (i know you wanted presentation c&c but i felt like adding what i thought in one post instead of ten.)
I'm not really feeling the green lighting either. Strangely, it kind of makes him look like he has jaundice. I'm guessing the main point of this portrait is to show off the anatomy and texturing and not a matrix lighting study right? I think a more neutral light color would be less distracting and better display your texturing and knowledge of skin color. Now there is nothing wrong with unique and colorful lighting set-ups, but if it distracts from the textures, maybe do just one green render, and the rest of the shots in a white or warm light.
As far as light position, I am a fan of the 3 point lighting set up with a lot of fill and strong rim light, but that is certainly not the only way to go. There are tons of videos out there on portrait lighting set ups (like this one on key light placement: https://www.youtube.com/watch?v=D_O6pbT7Ovw) You can also look for a portrait you like on Artstation or Google images and try to match the lighting in it. Then, you can post your reference along side your first attempt at recreating it here on Polycount, and one of us can help you match it closer.
Other thoughts:
-The specular highlight and reflections in his eye are important. Don't forget to add a light to make his eyes sparkle and make him feel more alive. Good job on your first image, but you forgot on the second image (the one with no beard).
-With good rim lights you can highlight your use of Sub Surface Scattering. Your first image has a decent rim light, but the SSS in the ear isn't really showing up. Right now it just kind of looks like the ear is too low res and the vertex normals are struggling, causing light to wrap around the surface in a weird way. Might be worth looking into.
-It looks like you are using multiple lights at slightly different angles to mimic one single key-light but you are getting a bunch of overlapping shadows on his right shoulder. A lot of rendering programs like UE4 and Marmoset let you increase the area of your point lights and spot lights to get softer shadows, extra fill, and larger specular highlights. "Area Lights" seem to be a favorite among real life portrait photographers.
-A solid back background can be kind of boring. A gradient background, a texture background, or a blurred hdr of an environment can help add interest and set a mood. The best backgrounds compliment the character while helping them stand out even more.
-For a 3d character, additional images of things like wire frames, material layers, UVs/texture maps, and work-in-progress shots are nice to see, and can keep viewers on your page a bit longer.
Replies
As far as light position, I am a fan of the 3 point lighting set up with a lot of fill and strong rim light, but that is certainly not the only way to go. There are tons of videos out there on portrait lighting set ups (like this one on key light placement: https://www.youtube.com/watch?v=D_O6pbT7Ovw) You can also look for a portrait you like on Artstation or Google images and try to match the lighting in it. Then, you can post your reference along side your first attempt at recreating it here on Polycount, and one of us can help you match it closer.
Other thoughts:
-The specular highlight and reflections in his eye are important. Don't forget to add a light to make his eyes sparkle and make him feel more alive. Good job on your first image, but you forgot on the second image (the one with no beard).
-With good rim lights you can highlight your use of Sub Surface Scattering. Your first image has a decent rim light, but the SSS in the ear isn't really showing up. Right now it just kind of looks like the ear is too low res and the vertex normals are struggling, causing light to wrap around the surface in a weird way. Might be worth looking into.
-It looks like you are using multiple lights at slightly different angles to mimic one single key-light but you are getting a bunch of overlapping shadows on his right shoulder. A lot of rendering programs like UE4 and Marmoset let you increase the area of your point lights and spot lights to get softer shadows, extra fill, and larger specular highlights. "Area Lights" seem to be a favorite among real life portrait photographers.
-A solid back background can be kind of boring. A gradient background, a texture background, or a blurred hdr of an environment can help add interest and set a mood. The best backgrounds compliment the character while helping them stand out even more.
-For a 3d character, additional images of things like wire frames, material layers, UVs/texture maps, and work-in-progress shots are nice to see, and can keep viewers on your page a bit longer.