So with observational drawing, as opposed to anything else, what would be the only thing you really need to use to know if you are being accurate with your drawing? answer- Measure and compare to what you are looking at. As a teacher, I am simply a new pair of eyes for you but the best thing I can do for you is to give you little tools for creating some kind of objective source of critique for yourself. So, try this: Rapid eye movement back and forth between the reference and your drawing. Look at one feature at a time. Or one area at a time. quickly back and forth. Look for the differences. Train your eye to see what's off. When you see the differences yourself, you will be unstoppable.

overall a good job. correct his right eye, or eye on our left. it's too low. we don;t want that to go into the painting stages.

Hey there! I think you might have tried to do two different exercises. In this case, it might have been better to try to draw the head inside of the box, rather than a full head with the Loomis method. Some of the lines in the box don't really converge the way they should, and doing the head inside the box makes mistakes like those more clear. But this is a really tricky project!