So I am pretty new to teaching and had very similar feelings before I dove in. My teacher training was very involved in adjustments and cues, but I still felt unprepared. The best advice a yoga teacher gave me to let me know I was ready, was that you are the one deciding what poses to lead in class. You can use your resources (books, Candace's blog, websites) to look up any cues that you don't feel confident in. It takes a lot of time in the beginning, but then things start coming more naturally. I don't know how to instruct someone how to properly align in grasshopper, because I've never taught it. If I ever chose to teach it, I would practice and use my resources to figure it out! I use Candace's pictures a lot to look at common mistakes in poses.