I'm rather late getting here, and most has been covered already.
I'm just going to run throught what basics i remeber from leveling me rogue, what i felt i did right/wrong.
First of all, i always ran dungon when i could, if people QQed about me dps, gear whatever, id say something like 'well i have to get my gear from somewhere, so by kicking me, i cant gear up' or something smart sounding like that, when it isnt that smart really, just common sense.
One thing i did wrong, was i ignored cooldowns, and randomly placed my talent points, always use cooldowns on boos fights, trying to solo elites, etc. Here is a decent combat leveling build, http://www.wowarmory.com/talent-calc...00000000000000
If link doesnt work lemme know, but this build is focused not entirely on damage output, but some survivablity, because you will be questing ofc and makes life easier for you. The part in combat with hack n slash, you can change this acording to your weapons, but axes/swords are easily the best for combat me thinks. Grab all the combat points first, then go for the assassination points. Glyphs, i cant remember which i went for while leveling, but glyph of SS and evisc are your best bets atm, then go for killing spree one. Minors, only one you'll really need is the safe fall one, its quite useful. Rotation, this has been said, but SS a few times, Slice n dice, few more SS's and evisc, repeat, only use Snd when its about to run our, around 3 seconds, no matter how many combo point you have on the target. When quests, dont bother using SnD, theres not much point if im honest, but it rocks in dungons.
Hope this helps!