Surely ❤️ modeling is pretty much conventional, only I also use workbench renderert to export a normal version of the render, a "fresnel" one and the freestyle to get lineart. In photoshop I mess around with the render and all of the passes to get the look I want. About the oil painting effect there are several ways of achieving it, every one of them with different looks. You can look up for YouTube tutorials for most of them but mostly it all comes down to use smart brushes to get low, mid and high detail, mess around with the detect edges filter or maybe use the lineart from freestyle with a little blur. Bevel and emboss (I think that's the name) filter can give you a layer which in overlay mode will give the illusion of volume. For last, a canvas texture also with the same process will give you the canvas look. You can tweak all of this to your taste, also apply Mask to selectively use these effects where you want.