Well played, the rogue is the most effective solo player in World of Warcraft. You can play and have virtually no down time whatsoever making experience gain very fast. Let me state here that questing in WoW is were a lot of the best items and experience is gained but that questing is not necessarily the best way to level up. In fact, it more often than not slows down your leveling ability with all the running around you need to do. After about level 35 you will still have quests to do, but it will be more effective to grind as they tend to send you across zones to talk to people. Once you have access to the Outlands, questing becomes a viable way to level up again as there is an abundance of quests along the way.
Solo Strategies
There are a lot of ways to play the rogue character. Some are more effective than others. Just randomly using skills is not effective. There should be a pattern to your combat so that you can get a “groove” when fighting. This way, everything is instinctive rather that you having to think to use a skill. Always a good thing when your reflexes make you select the right skill in a flash.
Ambush/Poison/Mutilate
Obviously, this is a dual dagger setup. This follows the Mutilate talent build and is very effective killing up all through your levels. The basic idea is to get to the opponents back and open with an Ambush, using Sinister Strike until you get 5 combo points and unleashing an Eviscerate (with Cold Blood if you have it). With proper talents, you can get 3 combo points off the opener. Instant Poison should be on both weapons.
Once you have access to Mutilate (level 40) the combo changes a bit. Ambush, wait, Gouge, wait, Kidney Shot, Mutilate, Mutilate, Eviscerate. You need to use Crippling Poison on the main hand here. This is a very effective way of not getting hit and dealing out some big numbers. You won’t kill as fast as a Combat build but you won’t need to heal anywhere close to as much.

This build works very well when you’re hunting creatures even or lower than you. When you deal out over 2400dmg in an Ambush, that’s a huge chunk out of your targt’s hit points. It does not work very well creatures above your level or on elites due to high armor resisting the damage from Ambush/Mutilate. It is my favourite build to level with but it is also the one that requires the most attention.
Cheap Shot
This build works with any type of weapon, though I would highly suggest a sword/mace for the increased damage from Sinister Strike. This build works great all the way to 70. You will open with Cheap Shot, which with Initiative will give 3 combo points 75% of the time. During these 4 seconds of stun, get as many combo points as you can so that you can get an Eviscerate off as soon as stun breaks. With Seal Fate, you can get the Eviscerate off before the stun breaks (3 from Cheap Shot, 2 from Sinister Strike). Combined with Cold Blood, this build is really devastating.
Applying Instant Poison is a good idea as well, looking at 10-15% damage increase. Even with the best poisons, you will be re-applying before the timer runs out on grind (killing for maximum experience gain) runs. The general idea is to take no damage for 4 seconds while trying to get the mob’s hit points to near 50%. You can take creatures on your level and take no damage with this build. Works exceptionally well against casters who will more than likely be dead by the time you Eviscerate.
This build works well into the 60s as you are offsetting the damage given to you with the 4 second stun to start. Against high armor opponents, the 4 second stun gives you more than enough time to get more damage than if you used Ambush. This build is also very effective in instances with groups. Eventually you reach a point where the enemies hit points are so high that your damage isn’t going to get them to 50% before the stun wears off and you’re going to take a minor beating.
Great for soloing when you can’t find any daggers. You have a consistent damage output and can fight any creature type with the same combo.

DoTs
This is a very situational way of fighting. Against casters it’s not all that effective as they’ll be dead before the DoTs wear off. It can work better against high armor opponents as you regular attacks won’t do a ton of damage. However, the higher you get, the more hit points targets have. If you’re doing 400 DPS with DoTs and the target has 8000 hit points and stuns aren’t an option, well you have 20 seconds of being hit to work through.