I remember the first time I tried to use the Pen tool in Illustrator back in 1989. I dragged along a curve that I wanted the line to follow. Instead of a curve, a straight line shot out nowhere near my original intent. Thinking it might get fixed if I tried again, I dragged along a similar direction. The lines only skewed out even worse. I closed the document vowing never again to try to use the dreaded Pen tool.
Later on I had enough nerve to try again with step-by-step instructions and finally mastered the concept of the Pen tool. It’s actually very mathematical with tangent lines directing the angle and height of the curves at each point.