The rouge is known for their sneaking and high damage dealing abilities. As a Rouge you will rest in the shadows and attack your opponents by surprise using various killer attacks. In World of Warcraft: Wrath of the lich king emphasizes this even more.

For a rough to play well you will need to keep track of your energy and ensure you use it in moderation. If you find yourself surrounded by a mob, it is absolutely essential to use your "Stealth" ability until the energy builds back up enough that you can take them out, or at least get out of the line of fire.

Using the rouge stealth ability is the key to success with this unique class. Keep in mind that you still can get detected by mobs, so here’s some advice to use the stealth ability:

•    When you go into Stealth mode, it is much more effective if you do it behind them instead of in front of them. This reduces the possibility of being detected.

•    You have more of a chance of going undetected if your stealth level is built up, rather than on the low side.

•    When in Stealth mode there are certain abilities that you can use. These include Backstab, Sap and of course the very powerful attack called Ambush. Plan and use the attack that best suits the situation.

When playing the Rogue in World of Warcraft's Wrath of the Lich King, it is important to ensure that make effective use of the combos that are specified for this class. Examples of an outstanding combo are "Slice and Dice". Immediately after using this, you can then use "Sinister Strike" for added insult to injury, throw in "Eviscerate" to make your mark! The secret to success with the Rogue in Wrath of the Lich King are Stealth, energy, and killer combos!

While leveling you want Agility and Stamina on your gear. That will give you Hit Points (so you don’t die), Attack Power & Critrate (So the mob dies faster). It’s also good if you find gear with AP, Hit Rating and Crit Rating. Try to avoid Strength, as it’s a fairly weak stat for damage compared to the others.

Blue quality items are normally better than green ones, and they last some levels before becoming outdated.
For a great rouge leveling and talent guide, I suggest you take a look at Dugi's leveling guides.