Its a little old

Hello! I love this character design! Your request was very general, so I touched on a few things... I moved the armpit curve slightly over, as it's meant to connect with the side of the pectoral (for which I included an example in blue). The character is also pretty curvy, and so I gave her a bit of a tummy so her front matched her back and legs in terms of fat distribution. The bottom of her chest wouldn't be so flat either because of the way they rest on the body, so I rounded them out. Given how sketchy your lineart is, I recommend giving small details, like her top strap, a bit of depth so they stand out and more clearly read as what they are. To do this, I just made the line a bit thicker and filled in the inside with the same colour as her top. Given the angle of the head and body, you would see her neck, and I moved her pelvis line a bit lower to have a bit more space between it and the belly button. I moved the mouth to the centre of the face, as while it's not uncommon to see it on the side, especially in more cartoony characters, it still looks a bit strange, and I would advise against it. Other than that, I added a few lines around her chest and hips that help add form. Her right hand is also incorrect, but that's still out of my skill set to help with, unfortunately... It's a good piece as is, and I look forward to any newer pieces you ever decide to submit to see how you've improved :) Hope this helped!