Here is how I began the drawing, I didn’t use the vertical and horizontal line shown by the guide. I did an angled line that touched the top of the lip and the furthest right point on the chin.
After setting in some vertical measurements I added in the vertical line similar in placement to the guides vertical line. This was very helpful in placing the extension of the nose.
There are many errors here, and I’m not sure exactly how to correct them. There comes a point in a drawing where my powers of observation and judgement obviously need honing. I’m trying to get away from measuring as much as possible because its not always possible when dealing with a more un-sanitized drawing environment. In a real environment I have to rely mostly on my own powers of observation, I have to be able to spot the most smallest difference without any aid beyond just looking and comparing the subject to the drawing.