Well let me start by saying, anyone that can get from 1-90 in 2 days without BoA is a god in human form or a bot of some kind. It would require almost non-stop play time wth minimal if any breaks for food, water, or even bathroom time.
That having been said, there are plenty of ways to level quickly, but they usually require some sort of aid. Questing is arguably the fastest method to level up and some people will purchase questing guides like Zygor to make the process even easier.
Equipping Bind to Account armor also makes this process a lot faster, since most of the BoA gear gives a 5-10% exp boost. It also levels with you, and is the equivalent of a blue quality item of the same level so it is actually very powerful up to it’s level cap. (Note that BoA gear can only be given to characters on the same realm.)
Choosing a duel-role character can also make it faster, since you can add dungeons to the mix, and at lower levels a single dungeon with quests can easily give you a level or two (if not more if you are fully BoA geared). Classes that can tank or heal can decrease dungeon que times by a lot.
Tanks are also amazing to quest with since you can easily grab 5 or 6 quest monsters and AoE them down, provided you know how to play the class well. When questing as a speed leveler you should NOT stay in an area until it is fully complete. Once you hit the level needed to move to a more powerful area, you should quest there instead. If you have a really good friend who is willing to level with you it can make things a lot faster as well since two people killing stuff will always be faster then one. If your friend is on a Refer a Friend with your account you both would get 300% exp boost when you play together so there is something to think about as well.
Giving your new toon the required gold for the riding and flight skills immediately will also decrease the time needed for traveling, but this can be expensive. (The fastest flying skills which can be gotten at 70 and 80 are 4k a piece at max Faction rep and 5k for no rep) While going for speed leveling it is usually best to ignore all profession skills until level cap, and I recommend ignoring pvp as well, since it gives the least amount of exp for the time spent.