I’d say you’ll have to learn Materials, Texturing and Shading always. Sculpting and Retopology will also be very valuable and don’t forget about Lighting.
Now, these are not isolated skills, that you need to learn in a specific order. Sculpting falls in the Modeling category, but you can leav that for later, since you’vce already spend a long time on Modeling, so you might want to switch it up a bit, to ‘keep you motivated’.
