
..and here's the photo I used for reference (found it off of About.com):

ALWAYS use reference! All good artists have used reference since the beggining of time! If it's good enough for Leonardo DaVinci, then it's good enough for you!
1.Block it out
The first step is to start with a monochrome background, or "underpainting."
This does not mean a "grey" or "black and white" background. This is a mistake many newbies make;
you want your landscape to have subtle variations in color; we are going to use the color from the underpainting
as well as the values.
But our first goal is to just paint the values. Pick a dark brownish color, "burnt sienna" is what they use in
traditional art, and start painting. First, I start with a rough sillhouette of the background.
2.Shape the forms
Next, I start painting in the background and some preliminary shadows. I do NOT use the dodge/burn or dark/light brushes
at this point! Dodge/burn can get some good effects, but used as a basic shading tool leads to some problems, leading to a
very distinctive, overly "shiny" look.
Instead, you should mimic traditional painting methods; Just put some darker brown on your brush, and lower the opactiy, building
up layers of transparency
NOTE: a word about layers. Using lots and lots of layers in Photoshop/PaintShopPro can be a crutch. This entire exercise
is done with just TWO layers. Working with a minimal amount of layers forces you to be bold and experiment rather than fret and
fidget over every little "mistake." If you make a mistake, try to fix it with the brush instead of the erase or undo key.
So I put in a bit of a gradient here for the background. I keep referring back to the reference image to make sure I am understanding
how this sort of landscape looks. I am using a large, soft brush, with pen sensitivity set to vary the opacity level, not the pen size.
3. Add some detail
Here I start putting in some dark lines. This creates a kind of rough "sketchy" look. The way I do this is by only now using the
darken tool (and only darken, not lighten), set to a small brush size, with sensitivity varying size. I set the pen density to about
75% so I get some granularity and texture as I work. I start putting in the darker areas.
WE ARE STILL ONLY WORKING ON ONE LAYER!!!!
4. Start the clouds
Avoid the temptation to put the clouds on their own layer. The clouds are PART of the sky, and you can't really separate the two, at least not with the style I'm going for. I use the lighten brush (and the lighten brush ONLY) here, with the same settings in the previous step. Occasionally I increase the size and lower the opacity to brush in some of the soft edges.
5. Add the color
Now, we add a second layer. In this case, I create a new layer above the underpainting and set its layer blending mode to "color." This will set the hue and saturation values of the underpainting to whatever is on the layer above it. I sample some colors from the reference photo and start painting in the colors for the sky.
6. Atmosphere
I start putting in some more saturated values for the blue. Then I do a gaussian blur of the entire layer to get it to blend in with
the peaks of the mountains. The key here is not to think so much in terms of layers; think of everything blending together seamlessly, you
don't actually want hard edges here.
I also start painting some low-opacity blue on the color layer over the mountains to start pushing them
further into the background. The sky and the atmosphere are kind of the same thing; the sky is not just up, but all around us, and as things
recede in the distance we are looking THROUGH Them, thus giving them a blue tint.
If this was a moonscape, we would not see this effect because there is no atmosphere on the moon. But here on earth, the human eye is trained
to interpret objects receding into the background as sharing the color of the sky, especially blue.
7. Foreground and Color
Now I start putting in some grass. Now, here we are in danger of falling into a standard trap, which I call the "dodge-burn-color-I'm-done"
trap. You see, these colors I'm putting in are "straight out of the tube" so to speak.
This term comes from traditional art, where painters have super high saturation paints in tubes that they put on their palletes.
These paints are bright super-saturated colors because they need to be as pure as possible in order to mix together.
However, very few experienced artists will just take paint right out of the tube and put it directly on the canvas unmixed because almost
nothing you're going to paint is going to EXACTLY match the color in any of the tubes.
NEVER use colors "straight out of the tubes" with no intent to mix them.
We've already learned that brown mountains can actually have a lot of blue in them, and the sky isn't always the same color. Red berries can actually have a lot of green or yellow in them depending
on lighting, and your brain will still see them as "red."
So, here's our problem: on a computer, it is super easy to just use a color "straight out of the tube." Just click on the color swatch and
start painting. The problem with this is the color from the color swatch is probably not going to match up to the composition that we've
already got going.
Traditional artists use a palette where they mix everything together to make sure that it will work. Then, they use
these same few colors to get all their ranges. Many beginning digital artists don't think to make a "virtual palette" on a separate layer
(a useful technique), because they think that's what the color picker is for.
So remember: THE COLOR PICKER IS NOT A PALETTE.
However, we digital artists have an advantage that traditional ones don't. On the digital canvas, THE PAINT IS ALWAYS WET.
So we can just take the eyedropper tool and fetch a nice color that we like and have an infinite amount of it. We can take the smudge tool
and start messing around and never run out of paint. So take advantage of it!
8. Subtelty and touch-up
Here I've taken an effort to subdue the colors. I take the underpainting layer and make it an overpainting, moving it above the color layer.
Then, I set the overpainting layer to "luminance" blend mode. This effect gets the same basic effect as the previous method, but subdues the
colors better. Also, I start using a low opacity eraser to vary the saturation of the sky.
Also, I start to depart from my reference image. The hill on the right side of the image is not reading correctly in my painting, so I change
it to become a little more clear.
9. Texture and the glorious Smudge Tool
Here I start to mess with texture. I take the smudge tool and set it to a medium-small size with a soft edge and start poking around.
I now have enough color variation and value in my image to get some good variation in my twiddlings. Working on the overpainting layer,
I start using the existing darks and light to define form better. I create little sub peaks and start pushing the shadows around to make
the mountains have more substance to them.
I also try to change some of the sky in the background into sillhouettes of mountains further
back (remember how the clouds and the sky are part of the same thing? So are the mountains in the background. I find it very hard to make
paintins "piecemeal" style with too many layers for this reason)
10. More Detail
Now I start to get detailed. I define some more peacks and regions in the mountains and tuck them into each other and start messing
with the foreground too. I add some more mountains into the sky's backdrop.
All of this is done with the smudge tool on the overpainting
Also, I notice that at some point I accidentally painted some transparent green on the overpainting instead of on the color layer.
At any rate, its a neat effect and so I keep it.
11. Messing with the Clouds
Now I start turning my attention to the clouds. Previously the clouds looked a little too "floaty", and didn't integrate well into the
space. I keep looking at my reference image and start integrating the clouds more tightly into their environment; again, I do all this almost
exclusively with my smudge tool.
I chisel away at the tails of the clouds to fold them into the distance and then use a larger, lower opacity smudge brush to blur them out a
little. I start trying to make the sky feel like a distinct whole and give some movement to the clouds. There are still some problems here
that need to be resolved.
12. Dynamic sky
Now we try to give the sky some substance. In the previous version it was just kind of sitting there not really doing anything. Also, the clouds are all going in different directions and don't see to be responding to one another in some coherent kind of weather pattern.
13. Shaping the clouds - more glorious Smudge Tool
So here, we start to push and pull the clouds into one another. The neat thing about having value and color on different layers is that
we don't smudge all the color away as we smudge the clouds around with my small brush sized smudge tool.
We get a really nice dynamic interplay between the grey, blue, and white. Now, the effect we are trying to generate is to get the clouds
and sky to feel like a coherent whole, sweeping past us through the foreground ans receding slowly and infinitely into the distance.
Obviously this is a very romanticist kind of cloud painting. We are going to have to work on the right side of the sky and make it a
little less overcast and cloudy over there to justify the bright blue sky; also it will be a neat little effect.
Also, we will have to go back to the landscape itself and make its detail catch up to the sky as well as respond to the lighting conditions
that this crazy cloudcover would give it.
14. Giving depth & shape to the composition
Here I try to give the picture some depth. I put some blue back into the mountains to push them back, clear open the sky on the right side of the picture, and thin out the clouds a little, as well as add some mountains in the background. This is done by painting blue on the color layer and using the smudge tool on the luminance layer.
15. Going totally nuts with color
Here I go a little crazy and add some wacky colors into the sky to see how it will look. I also work a little with the foreground to make the shapes make some more sense with eachother.
16. Going totally nuts with monochrome
As an experiment, I turn off the color layer to see how it looks. The subdued effect here is actually kind of nice.
17. Adding a figure
I settle for an in-between color scheme. Then, I stick in a figure to see if I can make the scene more dramatic. I just paint him in with black and then hilight the edges.
18. Fiddling with the figure
It occurs to me that the light was coming from the wrong side of the figure, and I didn't really like his static pose. So I redo him a little and voila! Stick a title in and we're done.
19. Alternative
And this is what it looks like without the figure, as an alternative composition.
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