My mods: decreases

To make a smooth and clean decrease line for neck and underarm, the first and last stitch are knit, and the decrease is made on the next /previous two stitches.
For the I-cord, I picked ut the stitches between the first and second stitches, leavig a straight neat knit column next to it.

Standed flat knitting and edges: fiddly.

It is useful to anchor the contrast colour from the row below onto one stitch before knitting it on the next row, or it will not look nice.