Lips are so soft and fluid – the best thing is to try and keep the drawing of them as simple as possible. Too much hatching and shading can get a bit messy!
You will find the index for how to draw cartoon people here: shooraynerdrawing.com/how-to-draw..
click the picture for a Pdf download sheet for this video.
Pencil is a much softer technique that lends itself to something like drawing lips, but this is a representational style and not a cartoon style. You can, of course, draw cartoons with pencil. They are not so easy to reproduce though, one of the reasons cartoons are so often black and white.
You will find the index for how to draw cartoon people here: shooraynerdrawing.com/how-to-draw..
click the picture for a Pdf download sheet for this video.