That looks much improved.
I use Photoshop all the time. Let me make a couple technical suggestions...
1) This last image is a good candidate for learning a bit about color overlay layers. Both the actress's head and the model's arms look a little pale to my eye. Now, I realize the model was probably shot there on location, so her arm is technically right, but if you wanted her to look a little bit more tanned, you could use an overlay layer and paint over the skin parts with a kind of gold color. Overlay layers can do unpredictable things if you're not familiar with them, so experiment.
2) More importantly, the shadows on the head do not match the shadows for the rest of the image. It's pretty easy to paint in fake shadows and highlights with the Dodge and Burn tools. Go in many very faint brush strokes and build the effect in gradually, a little goes a long way. This too can behave unpredictably if you're not familiar with the tool.
It's not Trek related, but if you want to see something I've done along these lines go to my website
where you'll find a pic of a girl I know that I did some adjusting to. The original image in the description part, and you can see that the lighting on the Photoshoped piece looks more incandescent; that's the overlay. Also, you'll note that the shoulder it not in a coat. The shoulder is actually a pic of another girl I know that I played with the color and even the shape of it and made it fit the first image. The back of her neck is a total fabrication which I just painted in place using color samples from the other skin parts of the image. Also, the red dress was originally a brown dress; I changed the color using the curves tool.
I don't know if you already know this stuff or not. You mentioned you were self-taught and I know Photoshop is big enough that the cool stuff can be overlooked if no one points it out to you.
I hope this helps!