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The right forearm in the first picture looks too short. The arm is bent at the elbow, so I think we should be seeing more of the arm instead of seeing it extremely foreshortened like that.

Is he sitting at a balcony/window and reaching towards the outside? It looks like there's going to be a lot of architecture-y details in the finished version. Pictures like this are a great opportunity to show off perspective skills surprised I would use a perspective guide to make sure it's drawn correctly.

With the second picture, perhaps your problem is that you're drawing/painting what you think a real person should look like. That's not going to work if you don't know what a real person is supposed to look like. Sounds silly, but a lot of us don't know it well enough to draw a realistic person offhand.

You should practice drawing from life (some reference images here and there are fine, but drawing from photos cannot fully substitute drawing from life). When you do draw from life, try to draw what you see, not what you think you see. Someone mentioned copying a photo flipped upside down; that way you will be forced to draw the person in the photo as shapes, not as a person, which reduces the problem of "drawing what I THINK I see."

Also, what are the light sources in that picture? Just the blue screens, or is there another light source?

With the first picture, it shows that you started sketching in the basics (such as the figure without clothing or hair), which is great. I'd recommend doing the same thing when you color and getting a quick, rough coloring of the entire picture first before you put those details. At the very least I would make the background blue before refining the figure.