Well let's see...first looking at a nose, you need shadow below the nose, and it's pretty dark,so it'll have to be darker then what you have going there.Another thing that helps is to darken the shadow between the eyes and the nose, but make a gradience of the darker shadow to the lighter skin tones as it moves down.You can also ass the slightly darker shades of the skin tones to eithe side of the nose to give it depth.Good luck with that.

-Oh and like Lori said, a bit on the sides of the nostrils.

I've been doing that but it never looks right...

are you looking at a ref?

Well....here's a tip assuming this is an Asian woman from what you have so far.Look up an Asian woman's face and try to incorporate the shadows on her nose on this pic of yours.

featherstone: no, making it up as I go along
Gigandas: thanks

wow.. no ref. You're good! I wish I could do that :-D This looks really good so far. Just follow Gig's advice and you'll finish it off really nice.

Beautiful skin tones you made. I think the nose looks fine.

i like this...nice job O)