Use of Mediums

I remember using charcoal and pencil for sketching and drawing during my years in NAFA. However after graduation, I began to switch to using ink pen (especially Pilot Hi-Tecpoint V5) instead, as a challenge of my skills.
It is easy to erase any mistakes if one uses pencil or charcoal, but not so with an ink pen; you just have to re-draw. By this way, I trained and sharpened my absolute observational skills. Some years later, I came across another interesting medium - the Dermatograph wax pencil (with a string attached for peeling new lead) which my students used it for outlining their artworks. Upon trying out its rendering effects, I realized this wax pencil really complemented well with my ink pen in drawing!
Thereafter, my personal drawing mediums and techniques evolved. From the collection of artworks above, you can see that I first used the ink pen to draw lines, followed by using the wax pencil to address the various tonal values.