Step 4
4. This is the last step. Here I added the top lip. To do this start at one of the corners of the mouth and make the shape of the top lip. To me it kind of looks like a sideways bow XD You do the same for the side view, but you have to keep perspective in mind. The dip will always be in the middle. If you consider this, the task may be easier. After that I added the dimple, and shaded in the top lip. The top lip ends up being darker than the bottom because less light hits it, that is unless the light source is coming from below.
The last thing I did here was draw a light line from each of the circles at the corners of the mouth. When drawing these lines go towards the bottom lip as if you're going to connect it, but leave some space between so the lips look less definite and more realistic.
1. In this tutorial I am going to try and help you learn the ways of realistic looking lips!! To begin draw two lines, one for the part where the lips meet, and another to define the bottom lip. If you already know how to make anime style mouths, do that! Start with simple, and just add stuff! If you don't already know the basics of mouth shapes, try learning the more simple two-lined style first. Then when you get the hang of it try the realistic type! 
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2. In this step, define the bottom lip some more. On the front view I curled up bottom lip towards the top line. Also at this step for the front view I made the top line shorter...it was too long! For the side view I just defined the bottom lip. 
3. For step three I added small balls at the corners of the mouth, this is where the lips end! I also thickened the middle of the top line where the lips meet to show the little dip lips have there. 
5. For guys, just give the lips less volume and make the bottom lip more flat. Also, make the little dip in the line where the lips meet less pronounced.