GamerPrinter suggested I do several different aspects of mapping with Pen and Ink, and I agree with him. This is probably the best way to cover the subject rather than just do one map.
When drawing with P&I, I always do everything in pencil first. I usually choose a softer pencil such as a 2b or 3b. This doesn't press into the paper (leaving an indention) and the softer lead is easier to erase with a gum eraser. Always use either a Gum Eraser or a white Plastic Eraser. The white eraser's sometimes come in pencil form that you can slide in and out, adjusting the length. They do also have them in blocks like you had back in first grade.
So, we draw some mountains, some rough looking inverted "V"'s. I then block in the areas that will be shaded.
Next comes the outline. Generally I like my mountains to have a thicker, darker outline, wider than the shading and hatch that will be used. For this and (all the rest of the outlines) I used a speedball dip pen with a Hunt 56 tip. Any of the softer, larger tips will usually work, depending on how you want it to look.
So that I don't run my hand across wet ink. (Dip Ink takes FAR longer than technical pen ink to dry.... a while, so be careful where you place your hands when inking.) I turn the paper at an angle where I'm drawing from Top>Bottom and draw all the lines in that direction at once. Then turn the paper so that I can draw the remaining lines all at once. Get into the habit of inking this way. Drawing lines that are all at the same angle on the same section you are working on. It saves time as well as not moving the paper around so much, increasing the chance of smearing wet ink.
Next comes the shading. There are several ways to do so, not all of them are shown here, but experiment and find what you like and what catches your eye. The first one I used a random hatch that didn't (tried not to) cross each other as it covered the shaded side of the mountain. I used tech. pens #1; 0; 00; and 3x0 to let you see the varying widths.
The next hatching is just a random series of lines sketched at different angles over the shaded part of the mountain. The top was done with tech. pens, the bottom with dip pens.
And last, full shading, similar to tolkien style mountains and fairly popular with the public. I personally don't like them to much but I thought I'd add this in. These types of mountains, and this type of shading should probably not be done with tech. pens as they were not made to 'shade' or ink in large swatches of black. These were done with Dip pens having wide tips that distribute a lot of ink at once. B5, 513EF, 56 and 99 were used in this one.
Practice drawing you mountains as you doodle and you will find they become easier and easier to draw. I've drawn so many mountains to date that I should actually own the Rockies.
This same principal applies to your hills as well. Because what is a hill but just a little mountains
If you want to see a certain type of mountains style, just request it and I'll do my best to accommodate your needs.