These are the selections of the leather texture, hat and green gramophone.
Using warping and resizing, I added the texture on top of hat. I also changed blending mdoe to hard light to get better shadows.

I added hat and gramophone cone over man.

These are three types of clocks and the wings selections, all selected with the quick selection tool.

Quick general tip:
- as you can notice, most of my selections were made with the quick selection tool as I really had a lot of them to do. The quick selection tool is a good tool but not as precise as the pen tool. So as a quick tip: each selection I made I had to defringe it (remove the extra useless bits and pieces around the selection). You can find this useful tool under layer/matting/defringe. I personally used the maximum width of 200pixels.

Added clocks and wings on hat. Masked parts of them using layer's mask.

Rooster and batery selections.

Added rooster and battery tank.
Colorized the tank using hue/saturation.
For both elements I duplicated layers, desaturated them and then changed the blending mode to hard light to get more of the natural shadows.

Venice Mask and helmet selections.

Added Venice mask, rotated it and resized it to better match man's face and eyes.
Added helmet on arms and neck, using warping, resizing and rotating.

Two types of clocks selections.
First one is for the back tank, second one for man's chest.

Added first clock onto the back tank, changed blending mode to overlay.
Added the square clock on top of chest. Used warping and changed blending mode to multiply.

These are:
- key selection;
- chimney (furnace) selection.
The final shape was created using the chimney selection in different positions.

Added two keys, one on top of rooster and the other one on the back of tank.
Added chimney shape and colorized it using hue/saturation.

Added some orange clouds and resized them to better fit the size of my own image.

Added other types of clouds on the bottom of my image.

Added another type of clock on the backround. Warped and resized it, applied different rotations and changed blending mode to soft light.

I used my primary green backround screen as I wanted to calm down the overall tones.
Here you can preview how it looked like before changing the blending mode and opacity.

Changed blending mode of the green backround to hue, and lowered opacity down to 28%.

Added different smoke brushes and some beautiful galaxies free brush.

Added a linear gradient layer from dark green (on the right) to soft brown (on the left).

Added another gradient, this time radial, using different tones of orange and brown in order to give my image some lighting effects.

Changed gradient layer's blending mode and opacity as follows:
- green gradient: blending mode overlay, opacity 46%;
- orange/brownish gradient: blending mode overlay, opacity 16%.
Made some corrections on the back tank using the clone stamp tool.
Added some gaussian blur and changed blending mode to screen to get the image to lighten up a bit (opacity 24%).
Added a brightness/contrast adjustment layer and a gradient map for shadowing.
Finally added some high pass filter for better definition: blending mode overlay and lowered opacity down to 29%.