Found a macro in a guide, a video or a guildmate's bars? See exactly what it does, line by line, then change it.
!! Macro window macros, not pad keys. !!
!! Macros go in the in-game macro window (Esc, then Macros). Bind one to a key or drag it to an action bar. They do not go on the pad. !!
Know what a macro does before you trust it. Every line is read back in plain English, every piece explains itself, and the checks flag the usual mistakes. Change anything and it all updates as you type.
Edit the text in step 1 and everything updates as you type. Simple macros can also be changed with the blocks below.
Spell it exactly the way the game does. Capitals do not matter; spelling does.
WoW tries these from the top and uses the first one that fits. Order is the whole trick.
Holding the key wins over everything in step 3. Leave the spell blank to cast the same one.
!! Check your keybinds first. This only works if Shift, Ctrl or Alt plus the key the macro sits on is not already bound to something else. If your bars use 1, Shift+1, Ctrl+1 and Alt+1 for four different things, putting this macro on 1 means holding Shift presses your Shift+1 button instead, and the macro never sees Shift. Put it on a key whose modifier versions are free. !!