The Rogue class in World of Warcraft is a pretty decent leveler if you pay attention to the talent tree and work specifically on selecting talents that will be suitable for soloing, leveling and grinding as well. So here's my tips on how to put together the best Rogue leveling build to get you to level 70 fast.
Most players spec Rogue primarily for dagger or swords, with fists and mace being distant follow-up options. For leveling, the best choice is going to be Swords, especially if you solo a lot. In fact, you should pretty much expect to be soloing a lot with the Rogue.
Rogue Talent Trees
The three talent trees for Rogue are Assassination, Combat and Subtlety. For putting together the Rogue leveling build for Swords and the fastest leveling speed, you'll be mostly concentrating all your points into Combat. By speccing mostly from the Combat tree, you'll increase your hits and also reduce your healing and cool-down time because you'll be able to dodge hits yourself much more readily. Less downtime naturally leads to faster leveling. So I think Combat makes for a more efficient build.
Your most crucial talent as a Rogue is going to be Sinister Strike so make sure you put points into Improved Sinister Strike (from the Combat tree) as soon as you are able (level 10). You will basically be using Sinister Strike in combination with Eviscerate from the Assassination tree. Spec Improved Eviscerate by Level 20 at the latest. Between Sinister Strike and Eviscerate you can wipe out virtually any mob by basically mashing Sinister Strike and then following up with Eviscerate.
Also from the Combat Talent tree, Precision, Deflection and Riposte will do you some good. Deflection and Riposte work together so you can deflect blows and then increase the damage on your own hits. For kicks, get Slice and Dice and you can change it up with Eviscerate when you get bored with that.
Keep speccing Combat, picking up the Duel Wield Specialization along the way. Ultimately though, your goal is to pick up Blade Flurry and Adrenaline Rush. They are a great DPS combination. Blade Flurry lets you attack two opponents and Adrenaline Rush increases your energy regeneration by 100% which makes it awesome!
Now if you want to balance out some talents from the Assassination tree, they will come in handy as mobs get tougher to kill. Malice, Ruthlessness and Relentless Strikes are particularly useful for laying on the damage, but you won't need them quite as much at lower levels so you might as well wait to spec them.
If you really want to increase your leveling speed and success as a Rogue, then you should definitely look into a Rogue leveling guide .
The Team iDemise Leveling Guides are available for both Horde and Alliance and they come with a terrific in-game map mod that will also do a lot to improve your leveling speed as you won't have to be constantly switching back and forth between windows. Everything you need will be right on your map and you'll be at level 70 in no time.