LOCK THOSE PIXELS AND FILL

This is a great timesaving shortcut when you have an object on a layer and you want to fill just the object with the Foreground color (rather than filling the entire layer with color). Press Shift-Option-Delete (PC: Shift-Alt-Backspace). What this does is turn on Lock Transparent Pixels for the layer in the Layers palette, fills the object on your layer, and then turns Lock Transparent Pixels back off. What if you want to fill your object with a gradient? It's a little more laborious. Turn on Lock Transparent Pixels by using the Forward Slash key (/) shortcut. Drag your Gradient tool through your object, and then press Forward Slash (/) again to turn off Lock Transparent Pixels.