WoW First Aid
First Aid is an ubiquitous profession in WoW, as nearly everyone will use it from early on for its bandages, which allow any class to do Mana-free healing. Also, because it is a secondary profession, learning it will not stop you from taking up the other secondary professions, or interfere with your two primary professions.
All of First Aid's items are consumed when used. To create bandages, you need cloths, which are obtained from killing Humanoid / Undead / Demon enemies. To create Anti-Venoms, you need venom sacs, which drop from poisonous beasts, such as Spiders and Scorpions.
First Aid is highly recommended to all classes as a way of reducing downtime between battles, by quickly restoring health after combat. Even classes with healing spells can benefit, since using a bandage after combat will conserve mana, saving the time otherwise spent drinking. Bandages can also be applied to the combat pets.
Bandages, usable in or out of combat, also have a large role in groups and raids. Characters who are not tanking or healing can back away from the battle at hand and apply a bandage to themselves, to help save the healer's mana. However, be warned that being hit (including damage over time spells) while applying a bandage will cancel its channeled heal. A remedy to this problem is to stun, fear, or find some other means to lose the aggro of that monster long enough to get some use out of the bandage. In addition, if you're in a raid instance or boss fight where your classes skills are ineffective (Such as anything with an Anti-Magic Field), or you're silenced or something similar, you can use Bandages to back up the healers temporarily (Just stay away from AOE attacks and you'll be fine)
An attempt to apply the bandage during the fight has a risk of loosing it without any use if the aid procedure has been interrupted by the enemy strike.