Power leveling is highly desired by many when it comes to playing Diablo 3.
A player might be tempted to spend a lot on cash on items since the auction house in Diablo 3 allows them to use real money to buy items (with Blizzard getting a cut from every transaction).
The best gear may produce better results. However, spending too much money on gear in the auction house is not the best way to do so even if you have all the money in the world to spare. At the end of the day, it is better to save that money because there are many ways to get the best gear in the game using the natural way.
For starters, questing in the right direction offers a better progression for each character even if going back to the same spot as before and killing the same monster over and over again seem very enticing.
Blizzard has changed the way the game runs now and what worked for Diablo 2 no longer applies in Diablo 3.
The returns on 'boss runs' is not the same as well because Blizzard is now encouraging players to diversify their playing style rather than go for repetitive grinding.
There are also higher difficulty modes in the game like the 'inferno' level which yield better drops for the player.
Another way to be more efficient at the game is to leverage on higher level players who are able to take on monsters that give larger experience (XP) gains. This method of leveling will help you to jumpstart your character in the initial stages.
You can also consider guides written by experienced players as they reveal what is the most effective path one must undertake if they do not wish to beat around the bush. This is also very effective for players who do not want to spend 16 hours in front of the computer each day to level up.