24 hours into teaching myself how to draw. What am I doing well? What do I need to work on?

While that one guy with the tall head was intentionally silly, I think I’m struggling most with proportions. I’m using a reference image for most of these, but none of the end results look much like the people in the photos. I’m also not using a grid as I’m doing this all with pen. I know I’ll eventually get it with practice, but is there anything specific I could try?