First up: Gathering
The easiest professions to cap are going to be gathering professions. They're a race, as the second the servers are playable, all the people gunning for realm-first herbalist, miner, or skinner will be out of the gates, grinding nonstop until they hit 525. What can you do to put yourself ahead of the pack?
Movement is everything. If you're going for herbalism or mining, your chance at the feat of strength will be largely based on the number of nodes per hour you can gather. Investing in the 310 percent flying speed is probably a must (as is, obviously, the ability to fly in Cataclysm zones), and paladins using Crusader Aura will have a significant advantage. Still, whether or not you can afford the perks or have a paladin, you still have a chance. This gives your competition a margin of error, but they may be less efficient or prepared than you.
Preparation is the key. I'd recommend reading these comprehensive guides to mining and herbalism. As stated in Kaliope's guides, a well-placed glove enchant can help you avoid thrashing around on lower-than-ideal-level gathering nodes.
Apparently, going from 450 to 525 herbalism or mining is a matter of an hour or so (in beta, without much competition). Add some time for competition and lag on live servers, and we're still looking at having most of the realm firsts done by the end of the first day. With this little exposure to the RNG of node population algorithms, you can easily overcome a disadvantage like not having 310 percent flight by simply being lucky.
Oh yeah, skinning... the red-headed step child of gathering professions. I looked around, and this is the most helpful post I found. Find some place with a lot of skinnable mobs, kill them as quickly as you can, and skin them. Ideally, find a major quest hub where every single level 80 DK is killing rats for their first few quests, so you can skin more than you kill. I went from 300 to 450 skinning in 45 minutes in Coldrock Quarry without killing a single mob.
The single most important piece of advice you need when trying for a realm-first gatherer feat is to spend every single second going for the next closest node that will help you skill up. Skip gray nodes, and know when you have to move to a new area.
Why did I put gathering professions first? Not just because I like doing the easy parts of my job before the hard parts, but also because I'm willing to wager 1,000 gold that the majority of realm-first feat of strength holders will have farmed their own mats. In that podcast episode I linked before the break, Kaliope pointed out to me that in every expansion so far, the basic mats needed to level crafting professions have been virtually unavailable for any price on the AH.
You see, people like to pair gathering professions with crafting ones, and even if they're nowhere near getting their crafting profession somewhere useful, they'll usually hoard all the mats they farm "just in case." Strangely, the hoarding instinct is stronger the higher the market value for the mats. This leads to much of the ore, herbs, and leather being gathered stagnating in bags or being used to level a crafting profession to 475 instead of being put on the AH.
As a side note, my plan is to avoid realm-first anything and simply start making farmed materials available on the AH. I'd rather sell a stack of ore for 1,000g now and use the profits from it to buy five stacks of ore when they go down to 200g. Unless you happen to be trying to max out blacksmithing on Drenden, however, this won't directly help you. Still, about 20 hours into Cataclysm, there will be a bunch of crafters jockeying for the realm first who may well be willing to pay 3,000g a stack if I put enough of them on the AH.
Preparation wins the race
That said, preparation is going to win this. Have a Cataclysm beta leveling guide handy, but be prepared to deviate from it if you discover a larger volume of certain mats. Gunning for a realm first is totally different than leveling on your own time, once the market price for mats has been established. You have to approach it as if cost were no issue, and to be honest, you can expect to pay a lot more than you would if you waited even a week or two.
You will have to balance lurking in the AH waiting for more stock dumps with going out and farming your own goods. Knowing how much of what you will need from the beginning will be a huge help with this, as it will let you capitalize on stock availability for raw mats even if you can't yet use them. Those who have two accounts will have a significant advantage on this, because they can stalk the AH and maybe even gather while they craft.
Insider Trader takes you behind the scenes of the bustling subculture of professional craftsmen, examining the profitable, the tragically lacking and the methods behind the madness.