Way back in the twentieth century, even before computer graphics and 3D visualization, I drew a lot using pencils and pens on paper.  Most of what I drew was representational (and most of that was science fiction-y), complete with accurate three-dimensional geometries in perspective.  Even my doodles were pictorial or geometric.  

But there came a day when I scribbled in the margin of a yellow legal pad, effortlessly and unconsciously, and then and there I recognized something new, and something worth exploring.  
That scrap of legal paper is long gone, but of my later efforts, the drawing below is similar in tone:  
This kind of drawing – intuitive, unplanned, abstract, and easy (don’t underestimate easy!) – was a radical departure for me.  I even had an affection for it, since so many of my other drawings, or the materials I was using, had become especially difficult endeavors.  I wanted to protect the integrity of these new drawings (especially from my own scientific inclination) even as I was attempting to identify what it was that needed protecting.  Safeguarding the intuitive process led me to think that these were entirely process-oriented efforts, avoiding goal-oriented thinking as antithetical to their success.  (Success in my eyes, anyway, which is all that matters here.)  While I tried to avoid an excess of aesthetic critique of the outcomes, I also tried to push their evolution by introducing color or constraints of gesture and style.  
The following drawings, while showing a variety of permutations, were all created spontaneously, with no definitive plan, no underlying rough drawing, no tools (such as compass or french curves), and no erasing…  
A typical effort in pen:
Adding markers to the pen:
Adding colored markers:
Constraining the overall shape:
Using just pencil:
Confining the style to sweeping strokes:
Straying into representational (if stylized) landscape mode:
Trying broader gestural strokes:
Going for a more textured (furry) look:
I consider every single one a success, at least to some degree, both in the process of their execution and in their aesthetic outcome.  I have many more drawings, and a lot more drawing to do!  
See http://www.tomsylvan.org/ for more.