• Your drawing ability is great.
• Usually this is the hardest part of portrait drawing and where many artists fail.
• Whatever had to be corrected after this was a piece of cake.

• When designing a painting or drawing we should consider both the positive space (the head) and negative space (void space that surrounds the head). This area should be interesting as well.
• The portions from the side of the head to all the borders of the picture plane should be different. It is better to "anchor" (having a section go behind the frame, in this case the neck and below) the portrait to the frame so the figure won't seem like it is floating in space.
• Another factor to take into account is color temperature. In the painting you submitted we have only warm colors with no cool colors for relief. The yellow background was too strong and warm.

My modifications:

After cropping the picture we now have different distances from the head to all sides of the borders. The background contains the complement of flesh color, grayed greens, which are cooler.The variation of values gives a feeling of depth enhancing a three dimensional look. I also glazed some hints of green into the shadows of the face. This gives a more fleshy look because skin is smooth and will reflect surrounding colors.

I suggest you do some research on Color Harmony to understand what color temperature is and the use of complements.

I blurred out some of the hair to avois a pasted on look.

Additional comments:

Fantastic job! Keep it up!