Scattered Shots is for hunters. 'Nuff said.

Once you reach level 62 and learn Steady Shot, it's time to start getting a firm grip on this thing hunters must learn called "shot rotation." If you don't - just casting your shots willy-nilly, as soon as they come off of cooldown -- you'll end up wasting a lot more mana and doing a lot less damage than a hunter who has his or her shot rotations timed right.

The video embedded above is a handy example of two basic shot rotations which we'll look at in more depth here, and it can give you a basic sense for how the timing of all this is supposed to work. But if it still looks a bit confusing, fear not: today's Scattered Shots will help you to make your shots less scattered and more organized, with helpful charts and fundamental knowledge about how to do this rotation thing. It really ain't that hard -- just a bit of info can get you pointed in the right direction, determining the rotation which is best for you.

Timing

Behold: The Inevitable March of Time. This baby is that irrepressible force moving the entire universe forward through the 4th dimension, bending a little around planets and stars, and getting totally warped out around black holes:
As far as you're concerned though, situated here in Earth's stable gravity, this is the immovable line you have to follow faithfully - all your shots need to be sorted up nicely along this line for maximum efficiency and maximum boom.

Next, meet Auto Shot. Don't look down on this one just because he doesn't have a fancy casting bar in the default interface. This is your source of mana-free damage, coming to you at regular intervals depending on the ultimate speed of your weapon. Once you get him going, he keeps on marching and doesn't stop till you tell him to, or until your target is dead.
Hopefully by now you've had a look at some of the important hunter addons out there, and you've got your hands on Quartz. You'll need that (or something like it) in order to see a waiting bar between Auto Shots. I call it a "waiting bar" instead of a "casting bar" because it only shows you the between Auto Shots, not the actual time it takes to cast them.

The actual Auto Shot casting time is a tricky thing. It takes 0.5 seconds to cast Auto Shot. Usually, this half-second is included within the last little bit of the time between Auto Shots, as pictured above, but if you are doing something else during that time, your next Auto Shot will be delayed. It may be helpful to think of your weapon speed minus 0.5 seconds as your Auto Shot waiting time, and then the last 0.5 seconds as its casting time: during that half-second you must be standing still, casting nothing, or else the next Auto Shot won't go off. Half a second doesn't sound like much, but if you don't respect it, the delays it causes can add up over time and reduce your damage. (For more about Auto Shot, look here.)

Finally, we come to your special shots, most often used in healthy shot rotations: Steady Shot, Arcane Shot, and Multi Shot.
After Auto Shot (which is free!), Steady Shot is your most mana-efficient source of damage, and is the staple ability in most hunters' shot rotations, with Arcane Shot and Multi Shot trying to fill in some gaps where you wouldn't be doing anything else anyway. (I'm not including Serpent Sting here for various reasons which we can discuss later, but if you want to include it, consider it as another instant-cast like Arcane Shot.)

Note how the damage from Steady Shot comes at the end of its 1.5 second casting time, whereas Arcane Shot hits instantly (followed by a 1.5 second global cooldown), and Multi Shot hits after 0.5 seconds (which is part of the 1.5 global cooldown). This is important for your timing, because Steady Shot will wreak havoc on your Auto Shot timing if not used carefully, as you can see in this example of a botched up shot rotation below:
See how messy that is? Not only did this hunter cast Steady Shot right before Auto Shot was set to go off, but he cast Steady Shot again too soon, interrupting Auto Shot's hidden 0.5 second casting time and forcing it to start over again. Most hunters have made both these mistakes before (and still do, on occasion) but it's really not good for us; it reduces our damage and guzzles up our mana! A bit of rearranging could have used that time much better:
This way, Auto Shot gets its chance to go off during that 1.5 second global cooldown after Arcane Shot -- you can safely fit Arcane Shot in such a spot just about every 6 seconds as it becomes available, with a couple Steady Shots and Auto Shots filling the time in between. The timing of this rotation allows for much more damage, in a much shorter period of time, and at much less cost to our mana pool.

Finesse

Now that we're feeling inspired, let's add Multi Shot to the mix:
Here, you can see lots of damage happening in just a little space, with all the available time being used up as efficiently as possible. Note that you can exchange the places of Arcane Shot and Multi Shot if you want to, and if you've got the timing right. Keep in mind, however, that this particular rotation is only for hunters with slow weapon speeds, nerves of steel, and internet connections of very low latency. It's up to you how much of a delay you are willing to tolerate, but if you're not careful, flawed reaction time and laggy latency can easily turn this lovely attempt at shot-rotational beauty into a messy disaster like the botched-up example farther above. You may wish to do another regular turn or two of the basic "Steady -> Auto -> Steady" maneuver until you are sure you can time your next Multi Shot or Arcane shot in exactly the right position.

Up to now, we've been working on the premise that you have a relatively slow weapon - but some hunters, especially Beast Masters, have lots of haste effects either on their gear or in their talents, which can change this setup dramastically. Supposing your ultimate weapon is hastened all the way up to about 2 seconds, for example, that leaves you without enough time to fit in those Arcane Shots or Multi Shots, without unhappily delaying your Auto Shot as well. In this case, it's best to revert to the good old standby rotation: "Auto -> Steady -> Auto -> Steady."
This rotation is very nice because, with such a fast Auto Shot, it does about the same amount of damage as the slower one up above, but it's also much easier to use and generally more mana-efficient as well. Note that with haste effects (including temporary buffs like Rapid Fire), your Steady Shot casting time also speeds up -- so it may be even faster than the original 1.5 seconds, and even easier to weave in between Auto Shots.

Whichever rotation you choose depends on your personal play style, of course. You may also find yourself in a situation where you want maximum damage and you don't care about mana-effeciency, in which case you can rotate something like this:
That brings us to the conclusion of the Scattered Shots basic shot rotation training session. There's a lot more to say about shot rotations, from adjusting because of bad latency and using helpful rotation addons, to finessing more power-up abilities and using special shots for alternate purposes. Feel free to discuss it all below if you like, and rest assured that you got the basics covered.

[No Elitist Jerks were harmed in the writing of this article -- Thanks for the inspiration!]

Edit: I corrected the Auto Shot graphs, and added lots of explanation to help clarify the tricky nature of its casting time. Hopefully now it is not only more accurate, but easier to understand as well.