So I just thought I'd post a macro that I've been using in some form or another for 10 years now, the Hunter's Mark + pet attack macro! This is great, it will make your pet automatically start attacking whatever you cast hunter's mark on. This will always cast the highest rank of hunter's mark you have, so you never have to update the macro unless we get to the point on Nostralius where Blizzard had disabled the /script commands.
/script PetAttack(target)
/cast hunter's mark