Here's that edit I promised:
I made two different ones, I was just trying to show how a bit of a color difference can change the feel of it completely. There are two light sources, one is coming from the top left, the other is bottom right(It would probably a light or candle of some sort thats making the light source), I mainly did this to make it a bit more interesting, so it doesn't look so bland. Now notice, they look gray but they aren't a true gray, in fact, the top one is full of blue and bottom is full of purple, once again, this makes it more interesting. Also notice how the lines get brighter as it gets closer to the light source aka the whole object gets brighter, this is to help the lines not be so harsh and of course, to make it look more interesting. Also added more contrast, didn't clean up the lines though I'd recommend you do, oh right, almost forgot, I also added straps so people will know that it's a mask(unless it's like, one of those masks that you know... don't use straps, you just put it right over your entire head).