Model
Model properly sized in mm units
Model has no hidden / frozen elements, no groups / linked objects
No lights, cameras, helpers, layers, particle view
All elements has 100/100/100 scale and correct normals
No any modifiers in stack except of turbosmooth
Elements properly named

Materials and maps
No missing textures
No unnecessary maps in environment / background / unwrap modifier
Material editor resetted
Materials and textures properly named