Link to website containing reference image: https://samuelearp.com/blog/how-to-paint-a-mountain-landscape-a-step-by-step-guide/ 

First I found a reference image of a beautiful landscape that had foreground, mid-ground, and background elements. Next I made a basic vectorization and colorization of the landscape using the curvature tool and editing the points with the direct selection tool, then changing the color in the color box. I decided to get rid of/minimize some of the black outlines for a bit more of a realistic feel, especially in the elements farther away because they should look less bold and more faded because of atmospheric perspective. I also used the brush tool to add detail into the rock vectors to create multiple smaller rocks out of one curve. 

I added some more detail using the brush tools, including water lines and highlights. Since it was summer, I went for a bright blue sky with lots of highlights and shadows to represent more of a harsh lighting. For the spring version, I think spring and summer are generally pretty similar, except maybe more things bloom in the spring. Also, I think the lighting is probably harsher in summer, but still bright in the spring. Therefore I kept the shadows and highlights in the spring and made them a bit duller, then added little dots of apples in the trees and flowers in the grass using the brush tool. When I altered this image for fall, I did not use the deep shadows, and while I did use some highlights, I toned them down so that the scene would appear more overcast in line with a gray sky. I clicked on the color box and adjusted the color manually for each vector. 

For winter I made the water look more frozen over rather than flowing water by tilting the image, holding shift on the brush tool so that I could make straight "icy" lines on the lake. I added snow on the peaks and trees which I made the whitest white to show how snow reflects light, and tried to add sparkles of light on the rocks but they ended up looking more like snowflakes. I did not add shadows here because the snow would be reflecting light in every direction, even though the sky is a bit darker.