A popular selling point of flashes is the ability to bounce the light. However, in real life, bouncing is a mixed blessing. The benefit of bouncing the flash is a softening and spreading of the light. You can also pick up a color cast, depending on the color of the ceiling. A better method is to attach a diffusing device of some sort to the flash.
Several types are available.
They spread the light, making it softer, and cost only about one f-stop. Even a plain white hankie taped over the flash head can soften the light nicely. When you store your flash for any length of time, remove the batteries. It's also a good idea to maintain the flash capacitor. If a flash isn't used for several weeks, the capacitor loses its ability to hold a charge effectively.