Option shortcuts (memorize 5)
Option + G →, Option + R →, Option + 2 →, Option + Shift + 8 →, Option + Shift + 2 →. Every character page on this site lists its Mac shortcut in the reference table.
Dead keys for accents
Option + E, then a vowel → acute (é). Option + ` → grave (è). Option + U → umlaut (ü). Option + N → tilde (ñ, ã). Option + I → circumflex (ê). Option + C → ç directly, no second key.
Character Viewer for everything else
Press Control + Command + Space anywhere. Search by name (“yen”), double-click to insert. Expand the window for the full Unicode browser with code points — the fastest way to identify an unknown character too.
Unicode Hex Input (the Alt+X equivalent)
Need Word-style code entry? System Settings → Keyboard → Text Input → Edit → add “Unicode Hex Input”. Switch to it from the menu bar, hold Option, type the hex code (20AC → €). Switch back to U.S. afterwards or your dead keys behave oddly.
Hold-key accents
Hold E and a popup offers è é ê ë. If holding repeats the letter instead, an old `ApplePressAndHoldEnabled false` default is set — restore it with: defaults write -g ApplePressAndHoldEnabled -bool true then restart the app.