Aaron Marino of alpha m. states that layering is going to be huge this fall and winter season. Light weight sweaters, cardigans, and vests are all part of layering. So, how to you execute properly a button-up shirt with a cardigan or pull-over sweater?
The shirt needs to be proper length if left untucked. Alpha displays the zones, which you need an inch to two inches from the bottom of your rise to the bottom of the shirt.
In regard to the light weight cardigan, leaving the shirt untucked is fine as long as the shirt is not too long. Wear the cardigan open and undone or button the cardigan (not top or bottom) center two or three.
The pull-over sweater needs to have the shirt tucked-in. Pop your collar out with the collar ends in the sweater. Hanging the shirt out of the sweater looks sloppy. Instead, tuck the shirt into the pants.