Updated December 18, 2011!
I have, in the past, called item enhancement my favorite mini-game in WoW, and this is still something that holds true for me. I think the satisfaction is similar to the satisfaction from a well-played game of Bejeweled, or maybe a crossword puzzle. You need to know what points you want various stats at and arrange your gems, enchants and so on to achieve the maximum benefit from your available configuration of stuff. Sometimes you just get lucky of course: I got two upgrades on the same night once and equipping both of them put me exactly at hit cap. Exactly. Situations like this are rare, though, and you're usually going to have to shuffle around some combination of reforging and enchants to get your gear where you want it.
The sort of basis of item enhancement is stat weighting. This sounds like a scary term, but it really isn't. All this means is that, when you're considering your gear, you give some stats more weight in your consideration than you give others. This is pretty intuitive at its most basic: as a physical DPS class, we're giving spirit no weight at all because we don't want any. Conversely, we give agility a lot of weight because we want a lot of it. The difficulty comes when we're comparing things like crit vs. mastery vs. haste.
Unfortunately, there's no always true for everyone all the time stat weighting. Depending on the gear you already have, what stat is best for you might change, sometimes pretty drastically. This can lead to misunderstandings when people do things like look at the armories of hunters in world-first guilds and then try to emulate those hunters' reforging even though they're raiding in a totally different environment.
There are tools to help us decide on our own stat weighting, with
FemaleDwarf being amongst the most popular. Even this isn't as easy as some would like though - you have to be careful to enter
your raid's buffs and debuffs as well as making sure the shot priority and settings match the way you play. If you're using a playstyle where you use Aimed Shot as your focus dump and never cast Arcane Shot and run a FD sim without changing the settings to reflect that, then just click the "best raid buffs" button even though your raid is missing the 10% haste buff, your stat weightings are going to be incorrect.
Now that I've made all of my caveats, though, I'll make an admission: for the most part, I don't do any of this stuff. There's a sort of default stat weighting that will generally be mostly true for most hunters, and I pretty frequently just go with that. Here it is:
Agility > Hit Rating to cap > Critical Strike Rating > Haste Rating > Mastery Rating
Again, this may not actually be your ideal stat weighting, but honestly? If you use these as your stat priorities, you'll generally be doing OK. Hit cap is, of course, 960 rating for most and 841 rating for Draenei. In general, I'd prefer to be a few points under the hit cap than be a few points over. This is because there is a finite amount of stats on your gear and hit rating over the cap is doing zero damage and is thus entirely wasted. Missing 1-5 autoshots out of 10,000 is preferable to getting no benefit from some of your gear.
This stat weighting will also be reflected in the sort of gear you choose. I strive to get all my hit from pieces that have both crit and hit, and my hitless pieces I prefer to be crit/haste. Further, I try to not have any piece of gear without any crit whatsoever, which results in most of my mastery pieces being crit/mastery. That means that when I'm reforging off my least-valued stat, mastery, the only thing I can reforge it into is haste. Some people see all of the haste I'm reforging for and think that I'm "stacking haste," and this just isn't so. I have far more critical strike rating than I do haste rating. It's just that haste is the best thing to reforge to on the pieces I'm reforging.
Gems and Gem Sockets!
Gemming is actually pretty simple these days. Agility is far and away our best stat, which is in line with it being considered a primary stat by Blizzard. Further, the requirement to activate our metagem is "socket at least 3 red gems". Therefore, we're free to socket straight agility gems, and as a general rule this is what you'll want to do, ignoring most of your socket bonuses.
Consider, however, the
Wentletrap Vest. This piece has two sockets, one red socket and one blue socket, with an attached 20 agility bonus. If you were to socket two 40 agility gems in it, you would be gaining a total of 80 agility from gems. If you were to socket one 40 agility gem in the red socket and one 20 agility/20 hit gem in the blue socket though, you would have 60 agility from gems, 20 hit from gems, and
another 20 agility from the socket bonus. That's a total of 80 agility and 20 hit, which is just more stats than you get from the two red gems.
What if the Wentletrap had a yellow or a blue socket instead of that red socket, though? Well, then to match the bonus you'd need another hybrid gem, bringing your total agility down to 60. People have done pretty extensive math on this and, for all specs, the extra crit and/or hit you gain from those hybrid gems doesn't outweigh the 20 lost agility. Your rule of thumb, then, is to only gem for socket bonuses which reward you with 20 or more agility per non-red socket. Here are the actual gems you'll want to use:
Metagem:
Item Enchantments!
Finally we get to the enchantments. There's not a whole lot of choice involved here, and all of the choice that is involved is budget-based. A lot of the top-shelf enchantments cost maelstrom crystals, and for most of us those are still out of reach. We probably won't be using all the best enchants until sometime in T12. I'm still going to list them here, though, because eventually there won't be an economic justification for using anything else.
Chest:
Back:
Wrists:
Cadillac enchant:
Agility note: this should be the first enchant you spend crystals on
Feet:
I'll just finish up with a couple quick notes on these. You may have noticed that a few Wrath enchants snuck in there, and that's fine. Maybe at some point they'll add a better glove enchant to the game, maybe not, but until then we're best off just adding the 20 agility. I also noted that the agility to bracers enchant should be the first thing you use your maelstrom crystals on, and I think this will be true for most of us. Replacing an enchant of 0 agility with one for 50 agility is just such a huge upgrade that it's hard to justify doing anything else first. Especially since the cloak and chest enchants are such minor upgrades from their budget versions, I'd let those slide until you and everyone in your guild had all the best melee weapon enchants, bracer enchants, etc. Like, I'd only really get those once you reached a point where there's a stack and a half of crystals sitting in the guild bank with no one using them, you know?
I haven't addressed profession perks in this post, and unless someone specifically asks about one I don't really plan to. Your professions are your professions, and taking advantage of your perks will generally result in a bonus of 80 agility one way or another. Other than that, I would pretty much expect any given person to know their profession bonuses pretty well, so it's up to you to make the best use of those.
Finally: please please just do the dailies and put on the tabards until you have the good head/shoulder enchants. It really really really doesn't take that long to finish those rep grinds, and using the crappy versions or the last-expansion versions is pretty much disrespectful to everyone else in your raid.
So that's it! It's taken me a couple months to actually write this thing, but hopefully it helps clear up any lingering doubts you had about gearing your hunter. Have fun!
