Many Misspelling you may find in my guide hope you forgive my bad english:$.

here i used Brightness/Contrast -150%/+100%

I use Brightness/Contrast 100%/67%, i darkened it a little with brush tool, i added shading and highlights with brush tool using white and black color because dodge and burn tool does not give the required result with this material

Copy and paste, resizing and structuring.

Dodge and burn for the metal and Brightness/Contrast for the wheels and brush tool for shading the wheels either.

Now i can obviously see the fruit of paitence, perhaps i'm not done yet but the result so far is telling me that i'm going to have a great image at end, okay, in next steps i'll avoid the making of the other leg since its not necessary, all i did was taking the parts of current leg seperately and fliped it horizontally and made their layers under the current leg then resized it to fix the perspective and darken it a little because it will be shaded from the inner side, in the next few steps i will make the cables and the hydraulic parts those appeared in this comperation step, about the other hand i just coppied the right hand and placed it behind the body and changed the shading and highlights a little.