The exposed paper of the drywall must be sealed before you apply any type of joint compound. I use "Guardz" made by Zinnser. Another one is DrawTite. When dry it will prevent the drywall from blistering when the compound is applied.
Apply the compound in two or three thin coats. followed by a sanding with fine sandpaper, being sure to feather the edges. spot prime the patches if you don't intend to prime the entire walls.