Front view of the chest.
Modify the edges like above, to make visible (full line) and invisible (dotted line).
Then Insert the edges like on the right.
Insert the edges as on the right image.
Insert the edges and to turn invisible those into dotted to have only quads in this zone.
Insert edges here to make the fold under breast.
Finally insert these edges and simplify the resulting geometry with Weld Target to remove the triangle.
Mark the median furrow while inserting these edges.
Finally add edges (full lines) and make invisible dotted lines to create quads.
There are nothing more but bands of quads for the junction arm-bust, giving best possible smoothing and avoiding concern in animation.
Faces of the arm were hidden for better legibility (Hide in the face mode).
Low poly images are above and subdivided ones below (NURMS with iteration 1).
Click on the images below to enlarge.
Do not collapse the stack because the reason of this type of modeling is to achieve low polygon mesh (LPM). We will use it for modeling accessories and subdivide it later.