What should I do to get a good tessellation material and fantastic render?

Thank you for taking your time!

I want to know what should I do to get my render looks good, what is the essential element, because I’ve already saw some really amazing render that done by other very talented artist, the result are fantastic and it shows UE4 can provide a extremely high-end result just like VRay or Toolbag2.
I’ve been searching and learning for few days, I learned about post effects(AA and more fine control for AO and GI), lightmass(overall light quality control), light map res(for shadow quality), but my materials are still looks ■■■■■■ in close shot, the mesh is jaggy.
I think my lighting is fine for now, but I don’t know how to produce a really good tessellation material, by referencing other artist’s work I’m really sure UE4 can do it, the problem is the way I do it is incorrect, please help me. by the way, I’m using 4K texture so currently I don’t think it is because my texture are not high-res enough.

Thank you all for your answering!