So if anyone needs macro help, ask me. I wrote and maintain the guide for macros on the UI & Macros forum here: Macros: Essential Information
For Misdirection, this is what I use:
#showtooltip
/use [help][@focus,help,nodead][@pet,pet,nodead][]Misdirection
This will use it on a friendly you manually target, your friendly Focus if you don’t have a friendly target, your pet if you don’t have a friendly Focus, and it will highlight the cursor to click on the target if none of those conditions are true. I generally Focus the tank in my raid and dungeon groups, giving me an easy means to Misdirect on cooldown without ever having to think about whether it’s going on the right target.
You can also add this in to other abilities since it is off the GCD.