I will say that I also needed to look up images, instructions, and videos online to fully understand the technique.
As per the instructions in the book not being clear, it was partly because there would be a couple paragraphs of explanations about a skill, followed by one sentence telling you to knit 2 inches or decrease every other row, etc.
When decreasing at the top of the hat (decrease on one row, knit all the next row), after several more paragraphs, on the next page, it told you to start decreasing every row once you got down to a certain number of stitches. I missed that note and had to back-track on a lot of stitches.
Advice: read the entire chapter before you start knitting. Then, highlight the instructions (or copy them on to a piece of paper).