There are many types of plackets guarding slits on clothes - here is a tutorial to make one so that you have a base for ...
On ready made or already sewn tops there are 2 darts that you can sew to reduce the waist ; the single point waist dart which is best for short tops (Those that end near the waist); these are best for ...
We always want our bobbins to be full, cupboards full of fabric and the sewing machine to move fabric forward stitching all the time. Well, almost always.