This is a really beautiful scene. The ship was already elegant, but the lights you added make it majestic. The clouds over the sea are a nice idea, they make a lovely transition between the sea and the nightsky.
In technical terms, the quality is good enough for a web display, but you could improve it if you wanted to make high-res prints of it :
- First, the cutting of the ship isn't perfect. Taking more time to improve and smooth the contours is a long and pretty boring operation, but I think it is worth it.
- There is also a problem with the clouds in front of the ship : They aren't very detailled, contrary to the ship, the planets and the sea. This makes a strange contrast and the picture seems less realistic. I think it's because the clouds were photographed by far. So maybe you could have tried to add details by painting over the clouds or adding clouds with Filter -> Render -> Clouds. Or maybe by adding an iris blur, to remove some details on the right edge of the picture.
- And finally, I believe you wanted to cover the rocks in the foreground with clouds but they're too transparent, so that it's hard to distinguish the clouds from the rocks.
Still, really nice work !
And sorry for my bad english.
I just learned something really cool that might help you with extracting clouds. Go to your channels. Pick the channel that has the best contrast and detail. Control + click to select it! then hit control j to make a new layer from it! after that, go to that new layer you just made and go to ( layer) on your top main menu bar and scroll all the wAy down to (matting) >remove black matting. This will get you a very clean selection . I hope this helps! It works great for extracting fire and water too.
Thank you so much for this useful comment!