Here are a few tips to level faster:
Questing:
Take as many quests as possible at the same time, try not to do quests one at a time. When entering a new area, find all the quests from NPC's first, before you start killing things. The principle of multiple quests becomes more profound the more you advance in level. Many times you will find yourself accepting a quest to kill 10 x monsters that you just got done killing for another item. It is tempting to:
talk to NPC --> Get Quest --> Do Quest --> Return = BAD!!!!
Once you get out of the first newbie stage and are past level 5, this approach will slow you down dramatically. You want to gain maximum levels, at maximum speed! The right approach, therefore looks like this:
Talk to all NPC's in the greater vacinity --> Get All The Quests you can muster. Collect quests like candy. Accept them from NPC's, accept them from other players (when you are in a group, players can 'share' quests). Quest A may say \"Kill 10 of monster X\", and Quest B may say \"Kill 10 of monster Y\". You will find that as you kill monster X, you have to plow your way through several monster Y's. In essence, you are completing two quests simultaneously. Doing multiple quests at once is the only way to fly.
Questing vs Grinding has been a big debate in this game. Some people just want to kill and grind without bothering to do quests. But quests are an important component of powerleveling as they give additional EXP, money, and items.
By taking the quest at the start, players have increased the efficiency of their character gains. Grinding is always good, but the benefits of questing is that you get additional exp for finishing a quest, and cash or valued items.
Don't Drop Quests:
It's so tempting to keep it....you just don't want to let go of that quest that's been in your books for several days. It requires you to run around the world - see this person, see that person...will take you 3 hours. Or that quest you forgot to do way back in Elwynn Forest, and now you're all the way in the Wetlands. DUMP IT.
Level Grinding still works!
This is killing monsters that are GREEN to you. You kill them fast and with very little down time. You can basically steamroll through dozens of con-green enemies in minutes! Spend an hour or two doing this and you'll see what a difference in EXP it makes! Small EXP gains over a long period time really add up.
Green quests are your friends!
These are quests that are 2-3 levels beneath you. When you get a bunch of yellow colored quests, sometimes you can just 'level grind' 2-3 levels, then power through the quests solo. It comes to this: If you are getting killed more than once doing a single quest, you are wasting time- its better to grind a level and do it later.
Play a Multi-Zone game. When you hit level 10 or so, its time to run to the nearest \"other\" starting area and do the quests there. You will do them fast, and get exp for all the kills (as long as they are colored green to you) Doing a load of quests 3-5 levels beneath you really racks up EXP fast.
Grouping:
A group of 2 or 3 is sometimes far better than solo'ing. Especially when a quest calls for \"kill X amount of something\". Use groups when they suit you. Leave a group when it bogs you down. The point is, GET IN A GROUP and you will see the EXP gains as well as the quests fly. On that note however, if the people in your group are not serious about getting the job done, leave. You will fare better solo any day than you would in a chaotic group. And if you can't find a group, just 'skip' that quest and go to the next one, and return later when you can. Solo when you can, but don't push it and waste 3 hours trying to solo a mission you could do in 20 minutes if you were in a group.
WoW is a group-oriented game. There are numerous quests that you just wont be able to solo, or if you do, you will spend 10x as much time on them than if you were in a group of 2 or 3. A few classes, such as Rogue, Shaman and Paladin are generally better at soloing than most, but even they will need to team up for many quests, and most of the 'elite' quests. The fastest way to power-level this game is to find two or three other players, get in a group, and steamroll through multiple quests.
How to SOLO nearly Everything:
So you just don't go for that team crap? No problem. If you are bent on soloing the entire leveling process, your secret will be to always try and stay a few levels ahead of the areas you are in. For example, most players enter a region such as Duskwood that is level 21-30 when they reach level 24-25. You will enter this level at 28 or 29. Everything at level 22-26 or will be green to you.
Still worth EXP but EASY to kill. You will take all the quests and plow through them solo. The only exceptions may be the elite quests which might still require you to team. And if you enter an area and everything is yellow, then you should 'level grind' until its mostly green. Level grind means going back to an easier area and killing a ton of either greens or yellows (so long as you can kill a yellow w/o much down time). The main strategy while powerleveling is to MINIMIZE down time. You want to be killing constantly w/o needed much rest in between.