Don't fold a drawing.
Don't stick the dividers into the drawing board.
Don't use the dividers as picks.
Don't fail to clean the table, board, and instruments when beginning work. Don't draw the lower edge of the T-square. Don't cut the sheets of drawing paper with the upper edge of the T-square and a knife; use the lower edge. Don't put the end of a pencil in the mouth. Don't oil the compass joints.
Don't put away the instruments without cleaning, especially pens. Don't use the cheapest materials. Don't use the T-square as a hammer. Don't screw up the nibs of the pen too tight. Don't use a blotter on lines that have been inked. Don't run the pen or pencil backward over a line. Don't fill a pen over a drawing.
Don't dilute drawing ink with water; if too thick throw it away.
Don't leave a bottle of ink uncorked.
Don't put away bow instruments screwed up tight; open to the size to fit place in case. Don't scrub a finished drawing too hard; it takes out the life.