How would I got about texturing low poly models like this?:

Everything in one diffuse map, so no PBR workflow.

Can someone give a list of topics/concepts/techniques I need to learn in order to create detailed textures like this for low poly characters?

Also what software would make the most sense for this task.

I already have modelled a low poly character so my current task is to texture it.

Thank you ?

Blender has a Smart UV option for generating a texture map from a mesh. Then, using the paint brushes built into Blender, one can paint on the mesh itself. I recommend Blender because it's cost-free.

Add same material to all objects on the scene and use it as a base to UV map all your objects. So now they share same texture and UV map file space. This way you have single texture file where all UV coordinates are stored and you can work on single texture for many objects. Once all objects are done add some simple colors and bake texture to know where each object is on the same UV map and if they are not overlapping where you don’t want them to. I’m assuming on a tight space like this you will use same texture part for quite a few objects :)

Use gimp and copy/paste various photos of hairy chests and chains layer blended on top etc onto the part of the mesh you want it to show. Once you have the UV coordinates generated you can work on the 2D image. In Blender you can export the triangle layout of a 3D mesh so you have a reference to what part of the 3d model maps to the 2d image.