Hey! nice progress man. Honestly, the best advice is to keep practicing more and more.
The fact that there's already progress between your tries 1 and 2 means you have a critical eye for your own work and have been able to make corrections.
That being the case, one piece of advice that has helped me a lot on regards to proportions and structure, as simple as it sounds, is to flip the image horizontally as you work on it.
I know there's a lenghty explanation for what it does, but basically, it allows your eye to view the same art piece with a "fresh perspective". Kinda like tricking your brain into thinking it's looking at a different piece of work. This allows you to quickly identify misproportions to correct them.
Try to setup a shotcut for this flip action (or just look up what the shortcut is), and do it frequently as you work on your next first try.
Once the image looks well proportioned flipped back and forth, then you know you got it right!
Keep practicing and going through the terms. I'm barely on term 2 myself and already there's a lot more to learn on regards to human proprotions and perspective!