As a freshman high school student, learning how to do contour drawings, we worked with Flair felt tip pens. The black ones. The school provided us with the paper which came in ream sized packs. At home I practiced on the back of paper with some sort of government legalese my dad would bring home from the office… basically copy paper in all the sizes it came in.
By the time I was a senior in high school, I was using Kor-I-Noor Rapidograph Pens and I loved them when they worked, but hated how messy they were to fill and clean. But the ink was permanent and they were (and may still be) the top of the line professional drawing pens. I also graduated to real sketchbooks, particularly the black hard-backed ones. I still have one or two of them with masking tape mending the edges and binding.
Today, I am still pretty happy with a Flair felt-tipped pen, but they are not waterproof. I still have a whole set of Kor-i-Noor Rapidograph Pens, but they sit unused.
Currently I’m hooked on two pens that I love. Both have permanent ink and do not run with I add watercolor or an ink wash. The first I discovered as a writing tool when I worked in an office: Uni-ball Vision Pens. I buy them by the dozen in a box. It is a medium sized line for me. The ink flows beautifully and the pen actually lasts a while. But these are not refillable and only come in one size choice. Thankfully, they are inexpensive and available via Amazon, or Office Max and sometimes even Wal-Mart.
The second pen I love is the Rotring Tikky Graphic Pen. They come in different sizes and use pigmented ink which does not run when painted over with watercolors or an ink wash. These are also not refillable but cost a bit more than the Uni-ball Vision Pens. I have found them in art supply stores and on Amazon.