First aid skill is considered a secondary skill and may be combined with another profession. Probably the best secondary skill you could learn, it can really come in handy in case of emergency. Here now is how to get started.
Firstly, you must have two main needs or items. Bandages or anti-venoms are a must for every first aid skills. The first time you get started, you'll receive rudimentary bandages, but you'll also need to have anti-venom or complete quests in order to get this. Numerous kinds of anti-venom are available and are very much useful in different situations that require its different types.
You can start on this is skill right from the beginning of level one. You won't have the best bandages yet because they will be available only when you've already advanced in skill, but it's better than nothing. Get an apprenticeship from a trainer to begin. This will get you started and you can always go back to learn more.
Soon after, you would have to buy the Expert First Aid - Under Wraps item. If you happen to be a member of the Alliance, you could find this at the Arathi Highlands. Horde players on the other hand could locate expert First Aid at Dustwallow Marsh. Once you get hold of this item, your skill level will bolster past skill level 150. Your goal is to reach 375, so by this time, you might as well be on your way.
Once you've reached the level 225, you'll have to undergo and complete the Triage Quest which would fastly advance you up to 300. Bear in mind however that once you get to 240, you could always return to your trainer to learn the advanced bandage wrapping and quickly move further in skill.
Anti-venoms are always available as you progress in skill. By reaching level 80, you'll be able to get your first one from your trainer. This will cost you about 1 silver piece and 50 coppers, depending on your source. By reaching level 130, you'll be able to purchase the strong anti-venom which costs about 2 silvers and 50 coppers.