The last facial feature to draw is the mouth. It is also very simple.
1-As usual, establish your guidelines and foundation.

2-For this example, we will draw lips that are slightly smiling. First, draw a straight line in-between the bottom of the nose and the chin.

3-Add a small dot to both ends of the line. Then add a small “V” shape in the middle. Since this is a 3/4 view, the “V” will be a bit distorted.

4-Erase a little of the straight line. Then draw a curved line starting from the “V” shape and meeting the edge of the lips similar to a mustache!

5-The last thing to draw are the upper and bottom lips.

6-You can also shade the lips but keep in mind that if your character is wearing lipstick, you should use a darker color.

Examples:
Some anime lips are very simple like these. I recommend using them on characters with big eyes. That way the lips wouldn’t be as distracting if you want the viewers to focus on the eyes.

Most of the time, these types of lips are used for younger characters.