Hey guys, I am in the process of adding some hills to the map I am currently working on and I thought I'd share my process with you in case anyone finds it useful. I use Photoshop but there is no program specific steps here. It obviously would be as useful for Gimp users or whatever. I use a tablet and although I guess it would be hard to do with a mouse accurately, not impossible. I wouldn't like to try it though. Been there, not going back.
There are other tutorials out there for this kind of thing and they maybe go into greater detail but this is how I do it.
First off, I select a small round brush with a dark brown colour. I had hardness set to 100% and the brush at 3 px. I set the opacity to around 65%. I also have shape dynamics and other dynamics on and set to pen pressure.
I keep the same brush for all stages of this, all I do is change size and opacity.
So for starters, on a new layer I call "Outlines" I just roughly draw in some hill outlines where they need to be. Try and vary the shapes and sizes to make them more interesting. Draw smaller, flatter outlines at the outside of your range and try not to make the hills around the edge too much in line.
Next I increase the brush size a little, I used 5px and lowered the opacity to around 30%. I then roughly shade inside each outline on another new layer called "Shading". You should know which side the light is coming from so start at the opposite side, where it is most shadowed and along the bottom of the hill. Don't make it perfectly straight at the bottom, allow it to bow out below where the outlines end to give the illusion of shape. Allow some darker spots in amongst the shading so the hills don't seem too uniform. You can be a lot more careful with your shading etc. but I like to keep it rough to help with the hand-drawn feel.
Next I increase the brush size again (I used 8px) and lowered the opacity down to about 20-25%. On a third layer ("Hollows") I quickly colour in between the hills in a very rough fashion. Where the hills are darkest on the shading layer I darken the colouring on the hollows layer, thus tying the hills together. I let the shading wander out past the edges of the hills in places so the whole range looks a little more integrated into the map and not just placed there. I call this layer hollows because this is the layer where you can suggest dips and hollows between the hills rather than just them all rising out of a completely flat plain. If you can picture how you think the land will be between the hills then simply darken any part that slopes away from your light source to imply shadows. Not done much of that here, just basic shading to connect the hills.
After that stage I often start another layer which I call "contours" and then dropping the brush back down to 2-3 pixels and raising the opacity somewhat I will draw lines where I imagine slope is going. This can also help suggest whatever shadowing you added in the hollows layer. I've decided to drop the contour stage on this map though as I want a slightly different look to normal but you can see the contouring I use on my Aronbor map or the brushes that Vhailor made from that map.
So here is how those first three layers look against the map.
They look ok but don't really fit in with the rest of the colour scheme I've gone with. So I set all three layers to "Soft Light". Now they're the right colour but compared to the darker mountains I have elsewhere on the map they looked a little washed out. So I copied both the shading and hollows layer and reduced the opacity on these two copies down to 50%. Now they look good. This is why I always keep the layers separate, so I can adjust each layer individually.
So here is the final range as it looks on the map.
I hope this is useful to somebody.