I seriously would go back to the sketch and observe your reference a little more. Her face is soft and she has a peaceful/happy look on her face. Your sketch looks angry and too sharp. For the coloring introduce a few more tones for your face.
I don't really know what else to add, it's pretty early in stage.
From looking at your drawing and comparing it to the photo - there's something you're missing. Her head is at a very slight tilt; while your drawing is not. That's one thing throwing you off.
Another is that you'll notice in that tutorial - that the artist is using values of color to block in the shapes and form of the head. It looks as if you're concerning yourself with details right away while in the tutorial, that's not the case.
Just mah observations - as luverly_marie said, it's pretty early in stage.
it seems that there is a fundamental difference in how you go about blending color and blending b&w... I usually just blend the b&w at the point they meet, but I guess I need to overlap and mix the color to get the right effect.
its all new to me.
this is just a quick test to see how it works... better, believe it or not. I'm using a speckled brush and overlapping the different colors.. alot.
I am pretty new to digital art to and around your level. This was my last work I did here . I think you shouldnt be afraid of using the lasso tool in photoshop to grab parts and shift them around and resize them to get that proportion right. Also sketch it cos your pencil work is quite good and scan it in. Dont feel that taking colors from certain sections in the image is cheating as it can be a way to drive your pallet.