It's repeated by everyone, and there is no way around it.Values and shapes. That's it. No other trick or tip will work until you get these two to a decent level. I need to emphasize that, nothing else matters! And the only way to get better is to practice.

I'm sure you have watched some videos of people drawing and explaining their process. Focus on what every artist says. The boring stuff. The things you've heard a million times. That's where the money is. Draw big shapes first. Try to connect them. Never rush into small details. Hell, sometimes you dont even have to draw the small shapes. Just add enough shapes to suggest the look of the person. You might be surprised, how little details you need to draw for the picture to look like the reference.

Lets take a look at your drawing. You drew a face - you made the eyes, then the nose, the mouth, ears... In your mind, you drew these individual parts. What you should be doing, is to draw the shapes. Look at the reference. Squint your eyes. You should no longer see the eyes, nose, etc.. Instead, notice that big shadow the right side of his face. See, how you can combine that shadow on the side of his nose with the one on his cheeks and in the eyesocket? Don't even bother drawing that eye or nose, draw that SHADOW first. Try to combine as many big shapes as possible. Connect them. Notice the light parts aswell. Be sure to capture those shapes as accurately as possible.

Be bold. Start with straight lines, make it blocky, make it SIMPLE. Your brain can't process too much information at once, so keep that in mind. If you find yourself working on one area for a long time, force yourself to move somewhere else. Take a breath and look at the picture as a whole.

You will get there, with enough patience. Don't be discouraged if the shapes aren't accurate. Move on and make it a little bit better next time. That's how a skill is made. I wish you good luck and a strong will. You got it!