BGs are a great place to be a rogue. Even if we aren't the killing machines we used to be our stealth and stuns can still go a long way. Some people say honor kills don't win a BG, but I beg to differ. If you can send one or two people back to their gy to have a fun game of "watch the rez timer" then that's two more people who aren't out there defending nodes and capping flags, and that, my friends, is a rogue's specialty.
Rogues have an array of cooldowns (my own definition: abilities that are on a cooldown of a minute or longer) that's larger than any other class, and deciding exactly when to use them is a big part of rogue gameplay. It's very easy to pop a lot a of cooldowns arbitrarily, but then they're not ready when you really need them. For instance, don't use Sprint simply to get from A to B. Unless there's and objective in danger there's no reason to use this ability outside of a combat situation.
Another good example is cloak. Lets say you're fighting a warlock and you kill him, but there's still a few nasty dots eating away at you, should you cloak them off? If you're not in immediate danger of dieing the answer is no. Sit down and eat to counteract the dots. You'll thank me when you're fighting the next caster 20 seconds later and you still have your cloak available.
One thing I find myself doing a lot is making last stands. I blow a bunch of cooldowns to simply live a bit longer despite the fact that, realistically, I have no chance against my opponent (or, more often, opponents). Try to avoid doing this, you're just going to die anyways and you're going to rez with everything on cooldown making you an ineffectual lump for the next few minutes. Obviously there are occasions where you should make a last stand to protect a node or cap a flag, but don't do it without good reason.
So the point is...cooldowns are our lifeblood. Don't waste them! BGs aren't like arenas, your goal isn't to simply zerg down one or two opponent(s). You're going to be fighting a lot of people over a long period of time, and things will go more smoothly if you pace your cooldown usage.
Choose your battles
Spoiler alert! Rogues are not warriors, and we shouldn't play like them either. Don't just rush headlong a pack of enemies and start crackin' skulls, that would almost certainly lead to a quick demise. A rogue's greatest tool is the ability to wait for the most opportune moment to strike. This is hard for me personally as I want to get right into the fight, but more often than not I find a quick assessment of the situation really helps. Try to identify healers, enemies with low health, or maybe someone who's already used a defensive cooldown (like opening on a mage after a blink).
The key to most successful stealth attacks is: don't let them see you coming. This is not always possible, but try to do it as much as you can. For example, say you're heading to LM, you should go stealth before you crest the hill. Don't go over hill and say "hai guise I'm here!" and then stealth, that's just going to lead to an aoe bonanza. Even if there's a battle going on don't assume people aren't aware enough to catch you going stealth. Don't give people a reason to do any more aoe than they already do. It's definitely not impossible to get an opener when your opponent(s) know you're coming, but it's a lot easier to get one when their guard is down.
You should also play with enemy nameplates enabled (I woulndn't bother with friendly nameplates, they just clutter your screen). It's a pretty basic concept, but I'm not sure how many people actually utilize this feature. As a rogue this does more than simply show you a target's health and casts, it helps you decide who to attack first. It sounds dirty, but you should try to open on the person with the least amount of health and kill them quickly. This is what rogues do, it's what we were made for, and nameplates are an easy way to quickly see who is hurting so you can quickly dispatch them.
See that druid healing right there? KILL HIM FIRST. As a rogue you are in a unique position to beeline straight to enemy healers without any interference from the dps protecting them. Pick a time where the enemy dps are occupied elsewhere and open on their healer (preferably mid-cast). The healer will have to defend himself and whoever they were healing will probably die. A person with a healer usually plays recklessly, imagine what will happen when their steady stream of heals is suddenly cut off.
It's not really easy to kill a healer, but most of the time you don't have to. You just want to lock down the other team's healer long enough for your team to get some kills. Once the healer's protectors are out of the way your team's dps can help you finish the healer.
There's no shame in running away, and this isn't a rogue-only tactic, but rogues are quite good at resetting fights if certain abilities don't fail us. For example, say you're fighting someone and you happen to see a large group of enemies rushing in to save that poor individual from the nasty rogue. If you're nowhere near killing your opponent then this would be a good time to cut and run. Sometimes you don't even have to use a cooldown to get away, just start running. One of my favorite tactics is to run through a group of allies, that way if they want to get to me they have to go through them first.
So that's it for now. Always remember to conserve cooldowns, choose your battles, kill healers, and run away. It can be easily remembered in the form of an acronym: C.C.C.Y.B.K.H.R.A. Maybe not. Hopefully these tips help you become a better rogue and a more productive member of BG society so you can propel your team to sweet, sweet victory! Believe it or not I still have a few more dirty tricks up my sleeves that I'm going to share in part 2 of this article. Stay tuned!