Go and grab the .blend file here

After I was satisfied with the topology I went in and started adding seams and unwrapping every object. In general I tried to keep the UVs as symmetrical as possible to make it easy to mirror over changes in the UV map and textures.

For the clothing it was important that I could just add a fabric pattern and it would follow the topology of the model. This quad-like wunrapping of the UVs helps save a lot of time during texturing/shading. To make this happen I used the pinning & live unwrapping features to align entire islands the way I wanted.

The body was the most complicated part since making the UV size relatively equal along the head while minimising stretching can be quite difficult. I unwrapped the eyelids and lips separately with projection from view to keep them as close as possible to the actual geometry. Afterwards I sculpted the UVs into shape further and stitched them back to the rest. The body, head & hands each have their own UV map and 1:1 UV space. This is to emulate a UDIM setup, which was not yet supported while making this character. By doing this I can use 3 textures with different resolution on the body mesh to gain more detail. Ultimately this wasn't really necessary for this character since the texturing & shading ended up fairly minimalistic but it's still a commonly used practice for film characters.

The only UVs that are missing in this picture are the eyes & inner mouth objects. You can find more about them in the .blend file from the link above.