First. You are using the term Pixar Style too freely. There is no single ‘Pixar’ style. Just compare the style of Toy Story, Brave, Up, Wall-E, Inside Out, and Good Dinosaur. You will see how many various styles that Pixar used. This would become even more divergent when you include the shorts like Geri’s Game, Knick Knack, For the Birds, Night and Day, Blue Umbrella and La Luna.
As for your model itself. It is somewhat decent. The head itself is well modeled and have pleasant forms.
However, she doesn’t really look like she is of African descent. This is a cartoon model so you have some leeway, but, just giving a female model a dark skin doesn’t make her African. This is a failure of design because you fail to capture in cartoon form the qualities of an African.
Also, the hair has shading issue as can be seen on the top of her hair. The modeling and material of the hair (including eyebrows and eyelashes) is rather plain. It lacks the effort that was given to the head.
And is that a horn at the back of her head?
As for the skin texture. Since this is a cartoon, you can get away simple textures. In fact, too much work on the texture would not go well with the cartoon model. Though if you want, you can add some subtle color variation. Maybe a tad of yellow on the forehead and some red blush on the cheeks and inner part of the eyelid.
Another aspect that you didn’t get right in this image is the lighting. The lighting here is just not suited for portrait shot, or beauty shots. It cast unappealing shadows, creates ugly highlights and a stray light is cast on her right cheek. Not to mention the extremely bright area on the lower left corner.
This is meant as a portfolio piece but it doesn’t really display any strong qualities as a 3D artist. You need to improve it some more.