I find it makes a difference if instead of drawing each line of my hexagram as I go, I draw it first in my mind’s eye. Closing my eyes and visualising clear, creamy paper, and drawing on each line with a broad-nibbed pen. Or keeping my eyes open and seeing the lines in the air.
At first I was scared of forgetting a line, getting it wrong, but it’s got a lot easier over time to see the whole hexagram at once. I don’t imagine I’d have the meditative concentration to do it with yarrow – but with my simple 16 beads, I enjoy the experience of starting out from a mental image of the gua.