Firefox has a very useful set of keyboard shortcuts. A complete list can be found here. These are the shortcuts you will likely use the most while browsing. If you're new to keyboard shortcuts, start by learning these.
Alt+Arrow (left or right)
Back or Forward page
F5
Reload
Ctrl + or Ctrl – or Ctrl 0
Zooms in/out on a page, Ctrl+0 returns to default size
Ctrl+F
Find
' or /
Find as you type link or text