The average human figure measures at 7.5 to 8 heads.
This can change depending the height of your character.
But, you must make sure to draw the character in the correct proportions.
Draw the head of your character.
Use a ruler to measure the head of your character
In this example the head is 1 inch
Use the ruler to measure the height of each row (in this example it is 1-inch)
Use the ruler to create the straight lines to create 8 rows.
In addition to understanding human anatomy, you need to also understand how clothing is drawn.
Use references to understand how folds and creases forms on the clothing as it moves with the body. Also, understand how clothing are stitched together.
When drawing, start with a sketch (stick figure), then build up your drawing.
Left drawing if the rough basic sketch. The drawing on the right is a sketch with more detail
Understanding how to draw the human figure can improve your sketching skills.
Sketches do not have to be perfect. They are meant to put ideas on paper and practicing on your drawing skills.
This example shows quick random marker sketches. In this example, I was practicing on poses and using gray tone markers.