hey! Here's a nifty thing to show how some poeople with background skills do it; the answer is "lots of brushes". I start iwth an sketch and block it out, and I use a lot of brushes that save me a lot of work. Here I show you my process step by step to help understand more.
Disclaimer: A lot of this stuff is on layers of its own, and when I shade things, I often set it to lock the colors so nothing I change in color goes outside of what's on the layer currently. When I use overlay or multiply or whatnot layers, I am often setting it to clip or lock to the layer below it. I'm not sure the terminology for Photoshop.
TIP: Watch Bob Ross sometimes, he is super duper good for this sort of thing.
This is the sketch.
I leave the sketch over the background for a wihle to act as guidelines; here it is blocked out, with ideas for where patches of dirt, sky, and grass go. They're all on separate layers, with the sky on the undermost layer and dirt under the grass. This is so i can use brushes and lock their colors a little more easily, which helps with blending brushes.
Here, literally all I have odne is take an simple grass brush (which is just some dashes) and sprinkle it over the top of the grass, avoiding the bottoms that meet the dirt for the most part.
Here, I've taken a softer brush to sort of soften it near the dirt, making it a little more patchy.
I took another brush with a slightly different grass shape to add some sprinkles and shading and color (all of this shading is just one brush but applied in 3 different shades - light, darkest, and neutral). It's really starting to look grassy now!
Here, I took an kind of chalky side to side scratchy brush and scored it across the dirt in a few different colors (two hues of a darker brown to add a bit of smooth feeling, as well as lighter) and used it (set to transparent) to erase a little of the bottom of the grass near the top of the dirt patches.
I took an pebble-like brush, smattered a lot of it over the dirt, erased a little of it, and then set it to about overlay 45%.
Thisi s the beginning of an forest off to the left! I took an special, odd-shaped brush, that I use for setting up forests of trunks and on mountains.
, and inserted it below the grass layer but above the sky and dirt layers.
More detailing with the same brush, but hues and fleshing it out more!
The beginning of the tree's leaves, with a different brush!
And here I go back to the trunks, with the same brush as the last step, but erasing parts of it to make the trunks stand out and stand from each other a bit more.
I took a sort of weird blobby brush and just painted it downward in peaks here!
Same thing here, just with some shades to add a bit more of volume.
I took an sort of coffee-stain brush and painted it all over anything green, then erased out parts of it to add a little more volume to the grass and leaves. It looks a little weird, but trust me, there's a reason for this.
Here, I realized the grass was kind of thin-looking, so I just copied the entire grass layer (all of this stuff was just on the green layer!) and copied it and shifted it slightly.
I decided I needed an fence in the background, so I drew out an simple fence with an regular lineart brush (just an basic circle brush, nothing fancy).
I used an slightly textured brush to add some shading on the prongs of it to add some dimension!
On an layer behind everything but the sky, I drew out some swirls of white with an simple slightly textured brush.
I made more swirls ,and erased some of it, trying to make it more irregular.
Here I put some blobs of yellow lighting on the bottoms of the clouds to add some dimension; they'll lookbetter in a bit.
Here it is, with the yellow a little chunked out by the same brush.
I took one of my cloud brushes (basically a soft, irregular cotton-ball shape set to scatter so it groups together), and dabbed around at parts of the clouds, as well as erasing a small amount of some of them.
And I decided the sky needed a little something, so here, a nice sun with an dusty (stipple) brush behind the clouds layer!
Colors are kind of hard, so I used an gradient on a layer above everything else (a circle gradient, centered on where I start it with yellow being the first color and a dark red being the second) on overlay 35% about, to help my color levels a little bit. Don't be afraid to use gradients.
I took a sort of wave-y brush on the layer under the overlays, but only made strokes above the greens in the pictures to add yet more volume, using a light yellow color then setting it to overlay opacity: 50%. The effect helps the trees especially!
At this point, there was nothing left to do but shadows, so the shadow of the fence and clouds got put down, made with an scatter brush and set to multiply 30%.
...And that's about it! hopefully, if you were confused about how some people block in backgrounds and/or use brushes in quantity to do things, that helps!