what I do, although I am not an expert, is use the guidelines for eyes, nose, mouth etc, It is important to start with the basic shapes first and then when the proportions are organized you can add the details. keep it up!

Michael Mattesi covers this topic in one of his videos: https://youtu.be/3sI3sYitpQs

The serial artists I've followed through life have all had their days of 'misses' where it comes to likenesses of a character over and over and over.....the factor I recall making them most comfortable was to get a model reference ingrained in their heads that, thought it may not have been absolutely spot on perfect with what they were drawing, it did allow them some "anchor points" to land on. The nose was just a "check mark", and the eyes a horizonal line with two black diagonals...etc. That and, well, lots of sketchbook work. Good luck!

Cool work, I think one thing that could help is practicing more with drawing consistently sized boxing turning in perspective, and using a system from someone like George Bridgman or Andrew Loomis may help.

try working the jaw, it is a little off and short man, but your hair got a pretty good design

Drawing faces is super difficult. I think studying the loomis head concept would help to improve your drawings :)

I have the same problem like this. Still trying, what I have learned is that you need to keep several features that will appear as silhouette correct. Like hair shapes, eye shadow area shapes, jaw and cheek bulge position and ratio... I'm not doing it very well at the moment, I think it's simply too small to be maintained that accurately. I think in professional works like comic and stuff they typically draw on much larger surfaces and scale them down so you can print those in books, and while those people drawing in these sizes, they omit a lot of stuff.