I don’t think any of those quick fixes are going to get you much.
The real problem is that the geometry that comes out of LDraw is pretty messy. For instance all the black markings on the face, mustache, eyes, etc. are polygons cut into the surface. With geometry like that no amount of set smooth or subsurfing is going to get you much.
If you want this guy to look GOOD you are going to have to roll up your sleeves and move some verts around.
A good first step is to tab into edit mode, hit the a key to select all, and then hit shift-j to join triangles into quadrilaterals. This won’t get rid of all the triangles, but it will get rid of all of them that can be joined automatically.
This by itself can give you a decent start if you apply set smooth AND hit the autosmooth button with a high-ish number like 45 or 50 degrees.
Of course, more the more mesh cleaning you do the better results you’ll get.
I recently spent a few hours on a minifig I imported from a 3ds file saved out of leocad. It was laborious, but I now have a perfect minifig base mesh. It’s just a matter of how good you want it to be and how much time you want to spend on it.