Taylor Swift

I think the portrait is very nice. Your mastery of anatomy is quite good, it's a very believeable portrait. I have no idea who the celebrity is or I'd comment on the likeness. There's a little bit of an up and down linear texture in the fabric of the dress and the background. It's hard to avoid in dark areas of a pencil drawing, but you can usually smear it a bit with your thumb. It doesn't really bother me, but it breaks the illusion a bit. As Doberlady said also, it's a bit dark. Is it on white paper? I would increase the contrast afterwards, though it's always important when you do so to make sure you don't lose resolution which can happen because if you have an image that only has 8 bits of color per channel when you do levels or brightness contrast adjustments, some of the values typically come out unused afterwards. Convert the image to 16bits per channel, then do your b/c and levels, then back to 8bits to make a jpeg. The shadow that you've captured in the image is a bit paradoxical. It suggests multiple light sources from in front of the image, to both left and right, and quite close to the image. If you drew from a photo taken with indoor lighting or flashes by a professional photographer, you will get shadows like that. However to preserve them in a drawing is unnecessary, and makes it look a bit odd. I prefer natural light and spontaneous/unposed photography, because the light sources used by professionals indoors do bug me a bit. You see a lot of photographers who will do their brightness/contrast adjustment to make the shadows disappear in the background, which I think is better, though it does leave a lot of their photography looking a bit stark and contrasty. Anyway, for your drawing, I would look at the shadow, and think 'how would it look in sunlight' or 'in ambient (non-directional lighting -- you can get shadows with this because typically the center of a room will be brighter and there will be a diffuse shadow on the wall, darker the closer the figure is to the wall). Use your imagination, it's the artist's most important resource!

(This is my first critique, so please don't critique me on my critique technique, lol. I am no art critic, but I was just paging through my messages and saw this one and liked it and started writing a comment and it got long, so I will just post it as a critique.)