Before I can actually design a logo, I need to be able to draw the images correctly. Even if I want a stylized sheep or thistle, I need to practice drawing the real thing first. Stylization grows out of reality, not the other way around.
For a few days, I carry with me the printed contact sheets shown in post 3 along with a sketch book and pencil and I practice practice practice. How do the sheep's ears work? What is the shape of the nose? How does one suggest wool in a line drawing? What does the sheep look like at different angles? What translates better, full body or head only? What does the thistle look like as a bud? As a full bloom? The leaves? I don't even try to make a composition until I know how each element works.