Rogue DPS help?

• Cast Slice and Dice as soon as you have your first combo point, then make sure it does not drop.

• Use Killing Spree, Blade Flurry and Adrenaline Rush whenever they come available.

• Put Improved Poison on main hand and Dealdy on Off-hand.

• Get a fast sword for an off-hand weapon, something like this.

The Elitist Jerks Pocket Guide to WoTLK for Rogues. Read it, learn it, love it. And do what is says. They may be jerks, but they know what they're talking about (and usually they're pretty nice, actually).

Okay, so first off, I want to encourage you to read my answer to a similar question by Kimptoc the other day. He's a DK, but nothing in my answer other than examples was DK specific, and the video linked there is probably going to do more for you than any amount of regearing or regemming that I'm going to recommend. For a frame of reference, I ran a heroic the other day basically naked (I was wearing 2T10.251, a pair of axes, and a trinket), and averaged 2000 DPS over the run, peaking at 4k on bosses. Doing 1.5k as a rogue and blaming anything other than simply not pressing enough or the right buttons is probably just making excuses. In general, unless you're not keeping Slice and Dice up, you'll lose more DPS to simple things like not always attacking something than you will to fixing your gems.

So, some advice for you as a rogue to improve your DPS. First off, you're combat. You have a Glyph of Eviscerate. You're specced into Improved Eviscerate and Aggression, both of which increase the damage of Eviscerate. So why are you using Envenom? Envenom is for Mutilate rogues. Eviscerate is your finisher of choice as combat.

Second thing, you need to make some macros. Nothing fancy, they should look like this:

 /startattack
 /cast Fan of Knives

That one will turn on your auto-attack when using Fan of Knives to AoE down large groups. Not autoattacking is the easiest way to lose damage without even realizing it while clearing trash. You can make a similar macro for other abilities:

 /startattack
 /cast Sinister Strike

That one ensures that even when you change targets, you never lose an auto-swing, so long as you're spamming the hell out of that main attack while you do so (as recommended in the video linked above).

In general, given the aforementioned replacement of Envenom with Eviscerate, the rotation you note above is fine. It's a basic 3s/5e rotation, which is pretty standard for combat. That said, you want to ensure that, over the course of a fight, that you NEVER LET SLICE AND DICE DROP. SnD is the single highest DPS ability you have as a rogue, and ever second that it's down you lose hundreds, if not thousands of DPS. It is more important to refresh SnD than it is to do just about any other thing as a Rogue (aside from staying out of the fire of course).

Your spec and glyphs are fine. (I'd question how you've spent your filler point, but moving it won't let you do more damage.) There's several things you can fix gearwise though. Replace the Meta gem with a Relentless Earthsiege Diamond. Get rid of the Crusader's Locket. It is by far the single worst trinket in WoW. It is absolutely, utterly, completely, terrible. As mentioned in other answers, get a fast offhand. Ideally a sword or Axe. There's a nice one in Heroic Halls of Reflection, and the BoE Runc mentions is a great starter as well.

How to Win at Rogue

1. Get Blood Weeper and Unsharpened Ice Razor from the new heroics.
2. Respec Mutilate.
3. ???
4. Profit

I know that will probably get down-voted... but it's totally worth it