(Ignore stars, I don't rate WIPs)
I love Korra! I can see you're on the right track here with this drawing. It's pretty accurate because korra is, for lack of a better term, "thick". She's boxy and has broad shoulders and a thick waist. She's a great character who doesn't conform to hypersexualised looks, and I think art of her should reflect that strength in her character.
Good job on the nose. I can see that you have a good foundation for it, and it just needs continued work, fleshing out the details.
As for the lips and mouth, I think you're at a place where you need to make some style decisions. Do you wnat your drawing to be realistic, semi-realistic or cartoony? If realistic, you may need to take a second look at the eyes and what kind of details to add to them. if cartoony, sort of teh opposite. Exaggeration and stylisation are the direction to go in.
The same for the lips. Do you want stylized or realistic?
What I see immediately is her eyebrows look a little odd to me. I don't have a picture of Korra on hand, so I can't remember her exact design, but I think you could bring the arch of her brows down a lot into a straighter line. Right now they seem very exaggerated.
I would also recommend looking up some stock images of nice toned arms to understand bicep muscles. I think her shoulder muscle ends a little high, and then her arms turn very flat. (I am probably not a good reference for this body type as Korra has much thicker, more muscular arms than me. I have very skinny arms)
One last question, where is teh light source for this picture? Is it at the front or above her? Really nailing down the light source answers a lot of questions for shading that might crop up later in the drawing.
Keep at it and I think this will turn out really well! Looking forward to the next version of this!