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You might be interested in taking both mining and black smithing as your professions. Many people think this is the best choice for warriors, it won't be as hard to keep yourself as geared and you will have more money from selling it on the Auction House as well. Once you hit 80 blacksmithing will help you get into end game faster thanks to the gear it can produce.
Warriors end up wearing plate at level 40. You will have the highest armor rating in the game, but armor rating isn't the on stat to concern yourself with. The extra bonuses many plate armors will give is also vital to your ability to tank.
The first trait to consider and focus on is strength, a very important stat. You find you will be focusing on various items that bolster your strength. Strength is the main ingredient to dealing damage, and damage is quite important even in tanking.
If strength is not available look out for stamina gear. Stamina is the stat which provides even more health to you, and this can be a huge deal since you won't be wearing plate until you are level 40. If tanking is going to be your focus you need to keep out an eye for defense gear.
Many warriors carry different sets of armor that will aid them in different tasks. You will have one set that allows you to dps better, which allows you to be a damage support in your group, but if you tank you will have another set.
Getting gear isn't the only thing you will do with it, you need to tend to it as well. Your armor will get dinged up from being in close range, so it is vital you make sure it does not break. Always repair armor as often as you can, and getting gold from your guild is not that uncommon.
A leveling guide might be something you want to look into to no matter if something as simply as reaching level 40 so you can check out plate armor, or if you have higher goals of something like reaching end game.
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