Well, I know, it's kinda strange to carry small sketchbook around and doodle in it with pen or pencils in our time of gadgets, tablets, electric cars et cetera.. I know but I can't help it - I just love to draw, and most of all I love to draw people. Myself, friends, family, characters from movies and TV, even imaginative persons - you name it.
For small doodles in moleskine most of the time I use ballpoint pen - I like ability to control not only thickness of line but (more important) the value of the strokes.
Ballpoint pens tend to leave nasty blotches of ink so I have a peculiar habit of smudging excess ink off the tip after every couple of strokes.
The main drawback of ballpoint pen - unability to erase - eventually became its greatest virtue. Despite these pens are cheapest tools in my arsenal they can teach highly valuable lessons - how to make right desicions straight away, how to overcome the fear of mistakes, how to find and keep likeness of person (SPOILER: it's quite hard, I fail often ¯_(ツ)_/¯)
At certain point I felt like I can draw with 2 or 3 colors (with awesome 4-in-1 pens from stationery store). Combining red and blue ink can create insteresting temperature shifts which makes illusion of skin tones.
And of course, small moleskine and pen can entertain you during long flights, I hate to sleep in airplanes so I draw all the time
So I think it's enough for the very first post here on steemit, hope it wasn't boring! If you like pen drawing like I do please share your thoughts in the comments below.