Facial expressions on World of Warcraft characters?

Hello everyone, so I’m pretty new to Blender but I’ve done a few pictures using WoW 3D models. I know how to make a pretty basic picture using backgrounds, lightning, items and so on, but one thing I really struggle with is facial expressions. How do I do those? I’ve tried so many options but I never seem to get it right, like, when I try to move an eyebrow the whole face turns into something that belongs to a horror movie.

So I’m asking you guys, if anyone would be able to help a newbie out. I would really appreciate it.