Not familiar with what I mean by "Greasing the Social Wheels"? Check out my introductory entry on the topic first.
About First Aid
On World of Warcraft, First Aid is one of the three "secondary" professions that can be learned by all players of all classes, no matter their other professions. Fishing and Cooking are the other in this category which can be learned by all.
First Aid allows a player to turn cloth into bandages - progressively more powerful bandages as the player's First Aid level advances. Bandages can be used as one of the many ways to restore health more quickly than natural healing allows, but the special benefit of bandaging is that it can be used for in-combat healing as long as the bandager and bandagee are not being hit (a hit will stop the channelling of bandaged healing).
Why First Aid Is A "Wheel Greaser"
In a party situation, it's not always fair to depend solely on the healer to restore your health from battles. And, as a healer, sometimes it's nice to save your mana and still get a quick heal.
While you may be fortunate and end up with group after group where the healer has plenty of mana to heal the fight and is able to recover mana for the next battle without huge long delays for the group, it's what you do to "pull out the last stops" on or just after a really hard fight that helps define you as an A-Team player versus an Average Player.
And if you're a Warlock who likes to Life Tap to restore mana, you're losing an INSANE number of karma points with the A-Team members if you're not bandaging yourself up after Life Tapping between battles, at least until the healer says they'll gladly take over helping you out there.
How To Use First Aid As A Wheel Greaser
The main thing you're doing by using First Aid is saving the Healer (even if the Healer is you) mana and as a result, allowing the group to progress more quickly, reducing the number of "mana up" breaks the healer will need. Sometimes, however, you're backing out of a tough battle to bandage for a moment to save your life (so you can contribute more DPS to the fight afterwards) when the healer has been forced to focus solely on keeping the tank up.
Here are some simple habits you can execute between battles that will be noticed by the A-Team:
Bandage yourself to full health after a battle has completed whenever possible
Hunters, use bandages as extra healing on top of your Mend Pet ability
Warlocks, use bandages to restore health after Life Tapping
Anyone - bandage someone who needs it between battles
During battles, it's not often all that useful to use a bandage, because being hit cancels the streaming heal of the bandaging process and bandaging can only be done once every 60 seconds. However, if you are not being hit and are a DPS character that can back out of a battle for 10 seconds to apply a bandage, the extra time you give yourself to "live to DPS another day" could end up helping the team more than if you had stayed, fought, and died.
What's the quickest way to level up First Aid?
Now that you see one of the important reasons to level up First Aid, how do you get it to a reasonable level, quickly?
Personally, I like farming dungeons for my First Aid materials, but that's because I have a max-level toon. Two runs of Ragefire Chasm, Two of Dead Mines and then about 6 wings of Scarlet Monestary and I'm at 225 First Aid and ready to do the quest in Hammerfall to up the max to 300.
If you're starting a new toon, however, consider leveling up First Aid more naturally - take the Linen Cloth you find from humanoids from level 6 to the low teens and turn them into bandages, and as you advance your level, the cloth types will advance, too.
If you're around level 40, consider farming RFC (or the Alliance equiv) for your Linen Cloth, or taking out humanoids in that 6-12 level range in zones you used to play in. Wool Cloth can be found on the Razormanes in The Barrens but is also present in Dead Mines and Wailing Caverns in piles.
And of course, if the prices are good because there's a lot listed, buy some from the Auction House!
And yes, Wool Cloth is ALWAYS that expensive (more than Linen Cloth or Silk Cloth, at times more than Mageweave Cloth)... but that's another topic for another day!