Jon's been doing everyone a favor and writing about all matters of constructed-related things and I can say for everyone here that it's been exceedingly educational. But Jon hasn't touched on a format that I can safely consider my area of expertise.
I am, of course, talking about limited. You know: draft and/or sealed. Specifically I'm going to touch on the more common of the two in this article: draft. Most of us rarely if ever play sealed. Truthfully, the two formats may be under the same banner, but they're vastly different.
Probably the most important thing to know about limited is the environment itself. In a booster draft, it's vital to know what to expect in terms of cards, in terms of how they interact with each other, and also in terms of what to expect other people to be doing.
I'll go through each of these points with examples.
Know what cards to expect in each of the slots and accordingly, what cards you can expect to see on the opposite side of the table. For example, in Kamigawa block, you can expect to have to deal with Glacial Ray, Horobi's Whisper, and various other forms of small removal.
Additionally, you can expect to sit across the table from a lot of 1-toughness creatures. When First Volley was originally printed as Shower of Sparks for one less mana in Urza's Block, it was worthless. But here, First Volley and Frostling are solid picks.
Mirrodin block was exceedingly bomb heavy, but slow. You had to be prepared more than usual, and games could often be very swingy.
Essentially, know what's in the sets and thus what to expect.
This is crucial. Kamigawa block - at the time of this article - is almost entirely spirits and spiritcraft. Splice onto Arcane barely made a dent in the limited environment when Champions was first released; you now expect to see at least one or two instances of splicing per game. It's no coincidence that the high picks are spliceable removal spells like Glacial Ray, Torrent of Stone, and Horobi's Whisper. You also never expect to see Kodama's Might later than fifth, and Soulless Revivals tend to go fairly quickly if you aren't paying attention.
Additionally, while Rend Flesh was a very high pick before Betrayers, Betrayers brought in an absolute ass-ton of spirits and consequently, Rend Flesh kind of blows now. More than that, most of the powerful legends on the table are going to be spirits, excluding game enders like Meloku the Clouded Mirror and Kumano, Master Yamabushi. Most of the major threats now are spirits.
What about our reject rare draft?
Well, first, there's next to no removal, which is why an utter pile like Personal Incarnation wins game after game. The environment's interactions are fairly unpredictable, but pay close attention. Just because mana cost isn't a very big deal anymore - most peoples' mana curves are starting at at least five - doesn't mean you can afford to fill your deck with fatties. That's a great way to get screwed by the one of us that was smart enough to grab that crappy low drop.
And remember: MORPH IS AMAZING IN A SLOW-ASS ENVIRONMENT. Morph creatures are NEVER dead cards. Even if you can't morph it, it's a 2/2 for 3, and that's Goddamn superb when everyone else is waiting until turn five to cast something worthwhile. Off-color morphs are never going to be dead cards, and you're not stupid for picking it up if there's nothing better in the pack.
Know what to expect everyone else to do. In Kamigawa block, you can expect half the table to be splashing red for Glacial Ray. More than that, black and green are oftentimes not even worth fighting over. Both colors are extremely overdrafted in block - black in particular. Does that first-pick Horobi's Whisper look tempting? It does to everyone else, so don't be a retard. If you're not in black already, don't fight for something that has BB in its mana cost.
Know the people you're playing with. You aren't always going to have this privilege, but you can rest fairly assured that with the group we have, you can expect Jon to be drafting blue or black, you can expect me to be drafting red or black, you can expect Brandon to be drafting green, and you can expect Sam to be drafting red.
This is all knowledge that you can pick up on your own. You don't even have to do that much research either; just play the environment and PAY ATTENTION TO WHAT YOU SEE.
When you get passed a pack in the first set of packs and you "CAN'T BELIEVE THIS CARD IS STILL HERE!" you may not want to say that out loud. I do anyhow, but that's because I'm a moron. Check the pack, see if the rare is still there. Then check the uncommons and take a count. Each pack contains eleven commons, three uncommons, and one rare initially. If there are any rares or uncommons missing, try to think if there are any rares or uncommons in the set better than the card you're looking at. If you're having a hard time thinking of one, congratulations: you're in your color.
Deciding on a color is often crucial. In some environments - like Invasion block or Mirrodin block - you can oftentimes afford to switch colors in the second or third pack. In Kamigawa block, this is absolutely punishing, and despite possibly being cut off by another player you may want to force your color anyhow and seek out a secondary color that's complimentary to your color and is being underdrafted. You'll know a color is being underdrafted if there's a wealth of it in the packs being passed around compared to the other ones, or if good cards are going abnormally late.
In most environments you'll want to avoid going into three colors unless you're certain you can support them. If you're in three colors, cards with two mana of the same color in their mana cost are generally out of the question.
So what colors are complimentary to each other? No, it's not the "allied and enemy colors" bit with the color wheel. Some colors just work better with each other than others. I'll go through each color combination here.
WHITE / BLUE
Extremely dependent on the environment. Kamigawa block, this is good, provided you picked up the removal available in white. White and blue have the strongest complement of fliers and tend to mop up green decks fairly efficiently. But you WILL need to high pick white removal (i.e. Cage of Hands, Pacifism, Reciprocate) in order to make this work. If you've got certain blue removal cards (i.e. Confiscate, Dehydration, Mystic Restraints), you might be able to make this work, too. But no removal? I wouldn't count on winning a damage race. You need the removal to keep the large black, green, and red groundpounders at bay.
WHITE / GREEN
Forget it. White and green are frequently so similar they could damn well be the same color. Don't even bother. When you pair white with blue, occasionally blue has removal. No luck here. It's not worth counting on white to shore up the weaknesses in this strategy. I have NEVER won with white and green together.
WHITE / BLACK
These two are frequently quite complimentary. White tends to have strong fliers; black has removal by the armload. Not a whole lot to say here. This is a good combo.
WHITE / RED
Largely dependent on the environment. Prior to the inclusion of Betrayers in Kamigawa block, this was dope fresh. But since Betrayers added a boatload of good spirits and next to no good samurai, this combination became very deficient. This is really up to your discretion, but it's quite tricky.
BLUE / GREEN
This is hilarious in constructed where it gets all kinds of tricks, but limited? Forget it. It's not quite as bad as white/green, but it's not great either.
BLUE / RED
This is a GREAT combination, and I think Jon'll back me up on this one. This color combination always seems to be viable in every environment it's in. Red has solid removal; blue has strong fliers and solid tricks. It's often weak on big creatures, but red has a tendency to shore up blue's weaknesses very effectively. It will oftentimes win well before the large creatures become a real problem and remember - it isn't too unusual for you to draft a large blue flying beater (Jetting Glasskite, Air Elemental, Qumulox).
BLUE / BLACK
These two are usually pretty good together, but tend to be a bit boring. They work well enough together but seem to have trouble winning games sometimes, in my experience. I think the fundamental problem with these two is that black doesn't really take care of blue's weaknesses beyond removal; its creatures are higher quality but aren't as good as the ones you'll find in red. As a result, blue/black tends to have more answers and less threats.
BLACK / GREEN
Absolutely amazing. Black tends to party well with pretty much every color, but here, black gets to clear the way for green's massive threats. Black also has excellent early game - not as fast as red or white but fast enough - and green will take over the late game. Because green's creatures are frequently so powerful and efficient, you can reserve your removal for the most serious of threats; green's creatures tend to be the killers in combat and not the killees. Additionally, black's Raise Dead spells (Soulless Revival, Recover, Urborg Uprising) allow you to get double duty out of your insanely large creatures. NOTE: Raise Dead is a bad card.
BLACK / RED
Solid combination, oftentimes very quick, but can be removal heavy and suffer the same problem that blue/black has: a lot of answers and not enough threats. Be careful to properly draft a LOT of good creatures and grab your fatties where you can.
GREEN / RED
This combination is good for all the same reasons black and green are, but not quite as good because it lacks the reanimation component. Still, a solid combination and one you shouldn't be unhappy to play with.
And that essentially concludes my first article, as it's gotten fairly long-winded and I'd like to think I've offered a lot of points to start on. Of course, there's much more to drafting than this, but this should at least give you a good launching point.