Quick Fill
Instead of selecting the Fill tool (G), you can quickly bring up the Fill menu
using Shift + F5. Even better, bypass the menu entirely using Option +
Backspace to fill with the foreground color or Command + Backspace to fill
with the background color. These keyboard commands can also be used to
quickly set the color of a type or shape layer. To preserve transparency
when filling, you could first lock the transparency of the layer by pressing /
and then fill, but there is an easier way. Pressing Option + Shift + Backspace
or Command + Shift + Backspace fills with the foreground or background
color while preserving transparency.