Flame Leviathan is a fight that I can get behind as a Rogue (pun intended). With no healing during the fight, and no true tanking either, all of our holy and prot friends are forced to play the DPS game along with us. I recommend asking for Chopper duties, if you're able to convince your raid leader that you'd be best suited in one of these fine motorcycles. They have the ability to strafe and move quickly: you should feel right at home. Playing one of the other vehicles may feel clunky (I know it does for me), but work with what you're assigned to. If you end up piloting a Siege Engine, remember to interrupt FL's Flame Vents ability.
Ignis is a fairly boring fight as a Rogue. Typically, it plays much like Grobbulus, depending on how your guild tanks the boss. You'll be following a giant around, stabbing or smashing him in the back, while your tank maneuvers him into position. The only caution on this fight is to wait for a teammate to be thrown into the Slag Pot before you choose to use any of your cooldowns. If your cooldowns are active (Adrenaline Rush, Vanish with Overkill) and you are thrown into his Pot, you will lose the effectiveness of those CDs.
Role: DPS, Add control
Razorscale starts with a few waves of Iron Dwarves and Vrykul before you fight the boss herself. During this preliminary add phase, you'll want to use your interrupts and CC to help clean up the fight. Interrupting a few Chain Lightnings or Dismantling the spinning whirlwinders will reduce your incoming raid damage and make it easier on everyone involved. When Razorscale drops to the ground, you'll want to use every offensive cooldown you have available to do as much damage as possible. Once she flies back up into the air, she'll be unattackable again. You want to bring her to 50% as soon as you can, and so the Rogue's ability to provide burst DPS is very valuable in this phase.
The fight that every Rogue dreams about: a static boss with a bonus damage modifier. As a melee class, your focus should be on attacking XT-002 and its very weak Heart (when exposed). You get to stand still, run your rotation without worrying about boss movement, and watch the ranged classes who are assigned to add duty. Make sure to time your cooldowns with Heart phases, in order to maximize your damage done. With Cloak of Shadows and Feint available to reduce your incoming AOE damage as well, Rogues are amongst the top choices for XT-002 fights.
Role: Interrupts, DPS, CC
While the "Can't Do That While Stunned" achievement is named very tongue-in-cheek after the most common complaint about fighting against a Rogue in PvP, the achievement is designed specifically with Rogues in mind. There is a caster mob named Stormcaller Brundir who is mostly stationary, and all of his spells are interruptable. In addition, he himself is stunnable for most of the fight as well. Rogues are especially well suited to lock down Brundir, giving your healers a much needed break. He has two main attacks: Chain Lightning and Lightning Whirl. Chain Lightning tends to be healable, while Lightning Whirl simply does too much AoE damage to allow through. Focus on blocking every single Lightning Whirl cast in order to minimize raid damage taken.
Feist, of the Roguespot Forums, had a very clever way of describing the Kologarn encounter. Basically, even though he has two large arms that appear to be off to his left and right sides, their "hit boxes" (where you can hit them at) are actually on his belt buckle. You want to get in real close to his waist, and face straight ahead. You don't need to turn in order to attack the arms, as a matter of fact you will actually STOP autoattacking if you turn too far to the left or the right. In the true definition of tunnel vision, simply sit on his belt buckle and use Tab to swap targets to the correct arm when necessary.
Role: Interrupts, DPS, CC
Auriaya provides Rogues with two different roles, depending on whether you're fighting her on 10m or 25m difficulty. In 10m, you are fine simply DPS'ing the boss while standing in FRONT of her during her Sonic Screech (think of Meteor from AQ and The Four Horsemen). In 25m, while also DPS'ing the boss, Rogues are typically asked to kick Auriaya's Sentinel Blast, which she always casts directly after a fear. Using Killing Spree, Cloak of Shadows, and other options for fear protection are key to ensure you never miss a kick, as this ability is very potent. The other fun things that Rogues can do on this fight is to stun the Feral Defender add that Freya summons. By stunning this add, you can ensure that it does minimal random raid damage, while also giving you more control over where the mob dies (as it spawns a void zone).
Next week's article will contain tips and tricks for the rest of Ulduar. Knowing your role in a fight ahead of time will reduce the amount of time the raid leader will need to spend explaining the fight, and will boost your confidence going into unknown encounters. Read up on strategies beforehand, and try to catch a YouTube video of the boss or ask a Rogue friend who has more experience than yourself.