Learning your spec
The most important aspect of playing a rogue is learning how to play a rogue. Regardless of what talent tree you choose, you need to know how each aspect of your spec and the class works. I always start by checking out the spec guides at Elitist Jerks, for combat and assassination respectively. Ieatpaperbag has a lot of great information on how to properly play either spec in PvE successfully, with enough detail to understand the reasoning behind the suggestions and enough data to support the statements. They've quickly become the first place I link to when asked about hit caps and rotations.
Picking talents in a post-Cataclysm world is fairly simple, as there's usually a cookie-cutter build with a few flexible points available to use at your discretion. Poison and weapon selection has been similarly boiled down to its core, and there's really no room for variation. Most of our decision-making comes in the form of choosing the right time to use our cooldowns and making on-the-fly adjustments to our rotations to accommodate for various fight mechanics.
Making good gearing decisions
Much of your DPS potential is determined before you ever step into battle. Figuring out what gear and gear modifications are best for you is very important to maximizing your DPS output. In order to make these gear choices, you need to have accurate information. In order to have accurate information, you need to figure out the specific values of any given piece of gear or enchant relative to your current DPS today. With several stat caps and varying equivalency points (EP) values, what's "good" is a constantly moving target.
Luckily for rogues everywhere, we have fellow rogues out there who are working on ways to help. In a joint effort between several rogues on Elitist Jerks, there are tools that can assist us in making good decisions. Aldriana has been working with Antiarc (developer of the infamous PoisonSwapper addon) on a master engine for rogue theorycrafting called ShadowCraft. Caffeine has written an updated web UI for the tool, although development is still being done. Currently the tool can't make gear suggestions, but it does allow us to generate EP values on the fly and compare our various sets of gear. Like any good tool, it takes some time to import the relevant data, but it gives us great information once that's complete. You need to take a few minutes and import your data into ShadowCraft manually. An armory import function is not currently planned.
Korner has been developing a complementary tool that lets us determine how to optimally reforge our gear: The Complete Rogue Reforger. It literally runs through every possible iteration of reforging possible until it finds the best result, and so we're guaranteed that we'll end up with the strongest option. In order for the reforging tool to give us results that are accurate for our characters, it needs accurate EP values for our individual rogues. Here's where ShadowCraft comes in. Generate your EP values in ShadowCraft, toss those into the reforging tool, and then put the output of the reforging tool back into ShadowCraft and make the changes in game. Korner's tool is always going to return the best reforging results, and so there's no reason to reinvent the wheel.
This boss does what?
Let's assume that you've already figured out what gear is best for your character, and you're enchanted and reforged optimally. There's still more to do before you're ready to embark on your first raid. Walking into a raid zone without any a priori knowledge of the encounters may sound like fun, but it also means that you're forced to figure out every single spell interaction yourself. Does Cloak of Shadows work on Magmaw's Pillar of Flame? If it doesn't, you're in a lot of trouble. Rather than try to test every mechanic yourself, rely on the power of the rogue community to solve these problems. There's a crowdsourced compendium of Cataclysm raid mechanics and their interactions with rogue abilities, tastefully organized and maintained by Zulkeir. Read up on any bosses you're going to attempt, and you'll already know what rogue tricks you have up your sleeve.
While knowing exactly what rogue abilities work and don't work is important, you're also going to want to know about the encounters themselves. Check out guides and videos to the raid that you plan on attending, and learn the fight before you ever engage the boss. Unless you're in a bleeding-edge guild (in which case you're the one recording), someone out there has likely already killed the boss and posted a video of it. There's no harm in educating yourself, and as I'm sure you know, knowing is half the battle.
Check back every Wednesday for the latest rogue strategies in Encrypted Text! We'll show you how to navigate
Cataclysm rogue basics, dig into new rogue mechanics, and gear up for heroics.