Untitled

Hello! These are two drawings I did as part of a 30 minute session (Left: 5 Minutes, Right: 10 Minutes). A struggle I'm having is with using measurements to get more accurate sizing-- I tend to measure in "heads--" using two fingers to approximate the length of the head, and then moving down the body in increments to see how long the figure should be.

However, I am still ending up with proportions that don't look quite right, especially in the legs. Any alternative techniques or advice would be much appreciated!

Advice/feedback on other elements of the drawings would also be awesome! Thank you for your time