I have broken it down and listed what I think is the top five.
) Read your Quest Journal Now we hate to snipe here, people, but the "L" key on your keyboard opens up your Quest Journal.
This handy little item contains literally all the information you need to solve whatever quest your given.
Check it early and check it often because if you're cluttering up the "General" chat channel asking "Where's the Wailing Caverns?" 47 times not only will you learn all sorts of new Azerothian insults, but when you eventually find the place, it's not going to win you any friends when you start looking for a group to explore with.
Your Quest Journal has directions so precise they make MapQuest look vague.
So to avoid this situation just read your Quest Journal.
) The City Guards are your friends - use them well.
This is kind of an adjunct to the whole "Read your Quest Journal" thing, but the other thing that clogs up the general chat channels is people asking for directions in the hub cities.
Fortunately Blizzard has come up with a simple solution - just ask a city guard! They'll give you directions to everything in the city and even provide you with a little flag in your mini-map! You know, the employment situation in Azeroth must be pretty bad when you consider that most of these guards are level 75 or so and can easily wipe out virtually every monster in the game and they're taking the time out of their busy schedule to help you.
The least you can do use their services.
I don't even think they get paid! 3.
) Every trade skill has a complement.
Players can only learn two "professional" trade skills (Fishing, Cooking, First Aid and a few others).
Be aware that with the exception of Enchanting and Tailoring, every trade skill has a "gathering" skill and a "crafting" skill.
Blacksmithing, for example, requires raw materials that can only be retrieved by Mining.
Be sure you select the appropriate skill; otherwise you will end up buying raw materials at auction or trying to trade your raw materials for finished goods.
) The Num Lock key is your auto run.
This should be obvious, but you'd be surprised how many players forget to use their auto run.
Auto run is your best friend.
During long runs you can be checking your quest log, your inventory, or chatting with friends.
Use it! 5.
) Control your Pets! This, of course, only applies to pet classes (Warlocks and Hunters), but if we had a gold piece for every Warlock and Hunter who left his pet on "Aggressive" we would all have a lot of gold pieces.
Your pets are tools.
They're used for very specific purposes.
Putting them on Aggressive lets them attack indiscriminately and can draw a lot more monster attention than your group is ready to deal with.
All too often a pet on the loose means death for the group and a long, boring corpse run.