Hello! I wanted to make this post as a fixed and convenient place to post some images of the process I used for making the picture.

The tools and resources: it's free!

This project was a challenge as, though I do work with CG imagery both professionally and for TTRPG stuff, I do not work much with photo-realistic images. My workflow was completely open-source (but my OS, which is Windows) and I used Blender and just a little of GIMP. The textures were also free resources, both the soil and the leaves textures were taken from textures.com.

Pain and gain: micro displacement

The technique used was micro displacement, which let me work with only a handful of polygons and let the textures do the rest in terms of detail. 

It has a caveat, though: the real geometry of the terrain can only be seen when the image is rendered. Luckily, Blender has the ability to use the viewport in "real time" render mode. It's slow, tedious and resource-consuming, but was totally necessary as I needed to adapt the tar puddles and drops to the terrain and the deer's footprints.

Speaking of which, I first tried to sculpt the footprints right on the terrain but the combined use of sculpt and micro displacement led to strange artifacts near them. And I didn't even get to make decent footsteps either. Lastly, I made a black & white image of the footprint and then combined with the displacement texture, so the deer hoofs are, also, micro displacement.

Render and post processing

This piece uses just little touches of composition as my motto is "make it look almost right just by hitting the render button". For example, the lens blur is in-render and not a post-production effect. The render, by the way, didn't take much as a denoiser was used to avoid huge render times.

So the composition was almost for optical effects and to make it look believable and close to analog photography as possible: some glow, lens distortion, grain, the flash illuminating the air and little more. You can see the process in the GIFs below:

To finish, a huge thank you to the guys at The Lost Bay discord server who helped with some tips and feedback to make the picture more believable.