, there is a list of line exercises that he recommends practicing at least 40 minutes a day.
Common types of bad lines:
Tips for clean lines:
Make sure your brush size isn’t too large. You want your brush strokes to be precise, which won’t be possible with a large brush size.
You’ll need to build-up your lines in some places to achieve a more 3D look. Be patient and build up the darker places by pressing lightly and going over your lines multiple times. Don’t just press harder, otherwise you’ll end up with inky lines.
Do your line exercises!
2. Wrong proportions.
There are a few different ways to check your proportions.
Draw guidelines from the reference to your freehand.
Drag your freehand over the reference.
Add a copy of the reference to a hidden layer and position it under your freehand. Only show the hidden layer when you want to check your freehand.
3. Eyes are the wrong size.
The eye circles represent the eyeballs. The size of the eyeball is roughly the distance between one tear duct to the other tear duct.
4. Head size and/or shape is wrong.
Beginners will often draw the initial circle and then never touch it again. Remember that you are allowed to refine your skull shape further so that it doesn’t look warped. Sometimes breaking up the top of the head into five separate curved lines will help.
Also, remember that you are drawing the cranium, which means that you might have to imagine where the skull is located under the person’s hair. A common mistake is to include too much of the person’s hair when drawing the skull.
5. Eye area is incorrect.
The top two corners of the eye area should be roughly where the eyebrows change direction. This is an approximation for where the front of the face transitions into the side of the face.
The bottom line of the eye area should coincide with the bottom eyelid. There is some ambiguity and inconsistency with the placement of this line, but the most recent recommendation is to place it on the bottom eyelid because it becomes a useful guideline for when you add planes.