Manage tabs, reopen what you closed, and fly around the web in Firefox. Mac and Windows shortcuts.
As with any browser, the biggest Firefox time-savers are tab management and the address bar. Ctrl/⌘ + T opens a tab, Ctrl/⌘ + W closes one, and the essential Ctrl/⌘ + Shift + T reopens the last tab you closed — repeatedly, in order. Ctrl/⌘ + L jumps to the address bar and selects what's there so you can just type. These four cover most of the clicking you'd otherwise do.
A few are worth singling out. Ctrl/⌘ + Shift + R forces a reload that ignores the cache — the first thing to try when a page looks broken. Firefox's reader view (Ctrl + Alt + R) strips a cluttered article down to clean text. And a private window is Ctrl/⌘ + Shift + P — note the P, where Chrome uses N. If you move between browsers, compare with the Chrome and Safari cheatsheets; most keys match, with a few telling exceptions.