Here are some essential shortcuts about Firefox you should know:
Ctrl + L – It will bring you to the Address bar to type your URL
Ctrl +K – It will bring you to your Search bar on the top right corner
Ctrl + Enter – Automatically prepend “http://” and append “.com” to a keyword entered in the address bar. Try this “Ctrl +L -> Type “WordPress” -> Press Ctrl + Enter”
Alt + Enter – Same as above for .org!
Shift + Enter – Same as above for .net!
Ctrl + <Plus Sign>/<Minus Sign> – Increase/Decrease Font Size
Ctrl + 0 (Zero) – Reset Font Size to default
Ctrl + F5 – Reload current page by Overriding the cache – An extremely useful option.
Complete list of other shortcuts here
Rushi's Ramblings 
I didn’t know about that Keyboard Shortcuts page on Mozilla. Many thanks Rushi.