Sorry for typing english here
Anyway, I am curious about how to outline black parts
Especially if hte hand is black, how can i make the shape of the hand be more visible rather than just plain black
Thank you much!

that's a hand or what kind of parts

u can use DRY BRUSH to outline it....but it will make it like a little bit old.

if  u want to outline it, but it look totally NEW, seems no way

actually, from 100% gross black to 100% matt black, there are so many different level of Black, this is also another method to show the 3D effect

Yeah, the part that i am trying outline is a hand of a resin kit.
I first tried to use really thin white paint, dry it a little, and brush it on
ended up making the black looks like covered in a layer of dust
Mm... Tamiya has only 1 or 2 types of black right? flat and gloss?
Because I am in usa, i have really limited choices of supply...><

What I suggest is that you can mix a little bit of white into the color of black, making it lighter than pure black.
Afterward, you can lining it with black.

I see, Thanks!