This is the first of my updates on my previous series of posts on Pet Control. Things have changed a lot in Cataclysm, but the one thing that hasn't is the importance of making the best use of your constant companions - those 25 best friends you have in your stables! :)
How to make your pet Attack, Follow and Move To:
The 3 leftmost buttons on the pet bar are Attack, Follow and Move To in that order, with the default keys being Ctrl-1, Ctrl-2 and Ctrl-3.
There are few ways you can change this to work.
Firstly, you can alter the default options for the Blizzard interface. This can be found by pressing Escape for the Game Menu -> Key Bindings, and scrolling down to Pet Action Buttons 1-10:
Pet Attack is actually given a second default keybinding, found further down and defaulting to Shift-T, which you can change as well (note: I've rebound Shift-T to something else in the screenshot below):
Secondly, you can use macros:
Some people like to combine these commands with other spells so that their pet attacks at the same time as casting:
/cast Hunter's Mark
However, I don't recommend this myself, because I always prefer not to link spells (so I can cast Hunter's Mark *without* sending my pet in, for example).
Using Pet Attack:
Pet Attack should be one of your most-used pet spells, particularly in raids and dungeons or when grouping. You really want your pet to be attacking the main DPS target, which it doesn't always automatically do.
If your pet is on Passive, it will not attack anything unless you use Pet Attack. In this case, you will need to use this ability every time you change targets.
If your pet is on Defensive, it will automatically attack the first target you hit and switch to other targets if the first one dies. In this case, you need to be careful - occasionally your pet will NOT be hitting the target you want it to be hitting, so you still need to use this ability fairly often to make sure it's DPSing the right target.
This is especially the case in raids, where your pet will hightail it for a target that's casting spells, but you don't want it to be DPSing. For example, your pet will often want to go back and whack an unreachable boss (eg. an immune or airborne boss) after an add dies, so you want to make sure it's hitting the next DPS target rather than trying and failing to attack something it shouldn't.
Using Pet Follow and Move To:
Pet Follow brings your pet back to your side, but unless your pet is on Passive, it will run off and continue attacking, so I tend to just hit Passive for the times I want to recall my pet (Pet Follow is generally the default state). I only tend to use Pet Follow after using Pet Move To.
Pet Move To brings up a targetting circle and tells your pet to stay exactly where you tell it to go, meaning it won't run back to your side. This is extremely useful for different situations where you don't want your pet to be next to you.
For example, if you're pulling to a tank using Misdirection, you can use Pet Move To to keep your pet out of the way - particularly useful if you're pulling adds back behind a wall where the rest of your group is.
You can also tell your pet to move to a certain position for easier or faster access to mobs (eg. moving your pet to where the melee DPS will start a boss fight rather than back where the ranged are, so your pet can start hitting that much quicker).
One thing to note: pet AI is quite advanced these days compared to what it used to be, but you still need to be careful in dungeons and raids (particularly in places like Gnomeregan where jumping off without dismissing your pet tends to mean your pet takes the long way around and pulls every mob on the way down). You used to be able to use Eyes of the Beast to jump your pet down and stay while you jump down yourself, but using Move To won't allow this because the AI won't find a viable path. Instead, you'll have to dismiss your pet and recall it after jumping down yourself.
Finally, one of my favourite uses of Pet Move To is when doing difficult soloing. You can park your pet away from you, Misdirect mobs to it, run past the mobs and then Feign Death once far enough away from them (preferably far enough away to auto-dismiss your pet), thus avoiding having to kill them. You can also put a Frost or Freeze Trap in between the mobs and the pet so that they'll be even slower getting to your pet.