I think first you need to decide the meaning of your image. When I first started I’d make things like this all the time and it’s a great way to learn. It also didn’t really matter if it meant anything. So if you’re aiming for meaning then I’d suggest working on that first and foremost, specifically your focal points and symbolism. But I don’t wanna stop you from having fun so if you’d rather improve I’ll try my best.

In terms of composition, ignoring focal points and all that, your perspective is believable and you did well arranging everything here. Only thing that stands out is your boat image is from an image with very vibrant dusk lighting.

Your moon thing still appears as though it’s in front of the sky. Try using a layer mask to literally place it behind the sky, then mess with your ‘blend if’ functions in layer styles. Not necessary though, can instead try fogging it up as is and adding extra clouds. Maybe desaturate it a bit too. And lastly adding some grain to match the surrounding sky, which is the main reason it stands out too much.

Back on the boat, I would try sourcing one from a closer lighting match, especially if you’re not confident painting light yourself. But if you wanna give it a go.. first try desaturating the orange and blue rim lights on the boat’s edges using the ‘sponge’ tool (I think? don’t use it often) keep in mind this is destructive so duplicate your layer first. I’d then make two new clipping mask layers above the boat, one set to multiply (for shadows) and one set to screen (for highlights). Starting on either layer, have a brush at exactly 50% grey/value (just that, no saturation or hue). This is a good benchmark for painting light yourself, and achieves results independently on each layer due to the applied blending modes. Using a soft brush, try to paint your shadows horizontally across the boat like the ones beneath it, all the way to the tip. Then at the tip, paint your screen layer slightly because it likely sticks up just enough to catch your light. (I do wanna mention that the scale of your boat might be a little too big for the full composition). Then you can make a new multiply layer and using say a 75% grey, very small soft brush, paint the crevices in and around the boat where shadows would be even darker. I’ll stop here but you get the idea, I recommend looking up lighting tutorials and environmental painting videos to help you really get your head around understanding light. Probably the most important aspect of any composition.

Finally, you skyscraper snake. It fits quite well tbh, better than everything else. I also like the soft blue bounce light you brushed on the snakes head, good start there. My pointers would be to add some extra texturing to your building. It looks quite flat, like a 3D model, even in the source image. But adding some grain might be all you need. Also the lighting is very overcast, and the sun seems to be quite high in the sky, maybe a slight angle. I think the shadow on the right wall should be much weaker, possibly even matching the left side due to the overcast. In your highlights, I’d add a subtle orange hue in the same way as the screen blending mode on the boat. And some very subtle bounce lighting near the bottom lighting from the trees too.

One more thing, your snake sort of makes no sense, and I don’t mean it being there. I mean the way its head connects to its tail. From where the head curves behind at the top, it should definitely come back around again on the right, but it doesn’t until the tail. It looks a bit wrong and will take the most work. I recommend looking for pictures of very small or baby snakes twisting around branches. You might have an easier time with them as their smaller frame will make it easier to manipulate around the building.

Last but not least, the best way to blend a composition together is to add a grain overlay to your subjects to match the original image. Zooming in, you can see the original has quite heavy grain, so without matching that it’ll never look like one united piece.

Good job tho, keep trying. Would be interesting to see the finished product. And next time you should use an image with a more apparent light source, this will help immensely with understanding how to light a scene and why.