Let us see some shortcuts that will help us to save some time when using Mozilla Firefox.
Alt + F4 => Close Firefox
Alt + F => Show menu bar and open file menu
Alt + E => Show menu bar and open edit menu
Ctrl + Shift + T => Open a recently close tab. This is useful especially if you accidentally closed a tab and forgot the url.
Ctrl + D => Bookmark the current website
F12 => Open Developer tools
Ctrl + Shift + A => Open Add ons Page
Ctrl + Shift + D => Open Downloads Page
Ctrl + Shift + H => Show history of websites browsed
I hope you like these shortcuts and will save you lot of time once you get used to it. Do comment out if you want to add a new shortcut.