Just hanging a knit top on a coat hanger may cause it to stretch out of shape. After I saw this tip in a video on the internet, I started hanging the ones I wear a lot. I had to watch the video several times before I caught on to how to do it.
Lay the top on a flat surface and fold it in half. Turn it upside down in a V shape. Place the top of the coat hanger between the sleeve and the bodice. Fold the bodice over the rack then fold the sleeve over. It's ready to hang.