Hi Kaldanen -
I'm glad you found some useful things in my comments.
re: "...How did you sneak the moon behind it?..."
There are many tutorials on this available on the web -- just Google {tutorial putting one object behind another photoshop}. Many are videos and they all probably do a better job describing the process than I could.
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re: "...I was wondering all day how you were able to make the trees come out of the dark and it finally dawned on me you must be adjusting the brightness and contrast of the picture! ..."
That's exactly what I did, but (a) there are many ways to do this, and (b) because the photo was so underexposed, you can only go so far before noise begins to overwhelm the image. What I did was to load the image into ACR (or LightRoom, if you have that) and bring up the brightness as much as I could in ACR. I also applied a bit of noise reduction in ACR. This left me with a vague suggestion of where the edges of the trees were, but weird magenta colored corners, popcorn noise everywhere, and unnaturally smooth areas in the image.
The magenta / red areas were the easiest to fix: I just painted over them with a soft blue brush set to "hue" blending mode.
The popcorn noise was also fairly easy to tame: I used the Dust and Scratches filter on a layer set to "Darken" blending mode.
The real problem was the complete lack of definition of the trees -- you could see there were trees there, but couldn't see any sharp edges, or detail in the centers of the trees. To fix this, I cheated. I pulled some photos of trees from my archive that were lighter against a dark background. I then superimposed one of these over the big tree on the left. Again, to get a realistic suggestion of detail in the center of the tree (eg, the trunk and branches), I had to use two slightly advanced features that you eventually will need to become familiar with: "blending modes" and the "blend IF" sliders. Look them up and play with them. There are lots of tutorials on these, as well.
The small triangular tree that's along the bottom edge, just right of center had to be handled differently. In this case, it was so featureless, I didn't even bother trying to fill in the center with fake detail. Instead, I simply wanted a better silhouette than the one on in your image. So, I brought up the lighting in that area, and put a silhouetted tree from my archive over that area, and changed the blending mode to multiply. That gave me a nicely defined silhouette. Obviously, my tree has to be a bit bigger than the area it's covering.
I hope the above explanation gave you an idea of what's involved. I know it sounds complicated, but it actually took me probably 10 times as long to write up the explanation as it took to actually do the work.
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For most people, once they have built up a reasonable skill set in PS, even more difficult than the above techniques and technical details is setting a clear direction for yourself -- ie, being your own art director. When confronted with a need or a job, there are an unlimited number of things one can do in the photographic and Photoshop realms. The hardest thing is to figure out at the start of the project what is the best direction to take, ie, a "vision" and a knowledge of your tools. After that, once you have passed the conceptualization and team discussion / consensus phase, what remains is a much more of a craftsman-like endeavor, not at all like the very cerebral and abstract approach needed at the beginning of such a project. Put differently, once you (and everyone else) are convinced that the "best" art for this band might be (say) a big moon in back of some trees, then actually implementing this is a much less daunting exercise of your skills.
HTH,
Tom M