Note, all of this is my opinion. In no way am I forcing anyone to believe my advice, though of course I am open for discussion.
Playing a Sub rogue in PVP a lot I find that many rogues I come across make common sub "mistakes," using the wrong abilities during battle, using useless attacks during fights, and of course just speccing in inefficient ways. This is my mini-guide to help those who may fall under this category.
1. Speccing into Master of Subtlety: Master of Subtlety increases your damage by 10% for the 6 seconds which you come out of stealth. This is a leftover talent option from back before Resilience reduced damage by 20%, and was meant to give Subs some burst from stealth. At this point in WoW, it doesn't provide any real source of damage. The average Arena fight lasts about 1-2 minutes, with 2 Vanishes(one from Prep) and the initial opener. In short, this provides about 18 seconds of benefit. It's unfortunately not too useful.
2. Glyphing Tricks of the Trade: This isn't THAT BAD of an option, especially since tricks is up so much for a Sub Rogue. However, with the way healers work, increasing sustained damage won't help too much overall. Tricks is oftentimes more useful as a burst option rather than a sustained damage option. 10 seconds is too much time for burst: 6 seconds is about right(that's probably how long you get the healer stunned for with KS). Therefore, more often than not this glyph won't be helpful.
3. Speccing 5/5 Malice: Once again, this isn't a BAD option, just not an efficient one. Lethality is important for many rogues because it allows them to put points into Lethality, which is a ridiculously powerful talent. However, a sub rogue can't get Lethality anyways; why then do they put points into Malice? 1% crit chance is about .8% increased damage overall, fighting someone with 1k resilience. It's better to just put 2 points in so that you can get Improved Backstab and then go back down.
4. Blood Splatter/using Rupture: Rupture is a good ability for sub rogues. However, the overall damage is based around having a druid or a warrior apply the 30% increased bleed effect. It does deal a great load of damage and go through plate, but fails to finish the job when a healer is involved and CC is more important. If you 2v2/3v3/5v5 with someone who has a bleed debuff, or need to apply DoTs for whatever reason(*cough*Rogues), it is useful. Otherwise, it can cause some problems breaking CC.
5. Opening with Ambush: Ambush is a good ability, but Cheap Shot is significantly better in terms of utility. If the target is already stunned or DR is involved, open with an Ambush. Otherwise, Cheap Shot or Garrote.
6. Premeditation: Premeditation is a great ability, but comes up somewhat useless when used in conjunction with Cheap shot or Ambush. In both cases, the 5 combo points are preserved for the KS, and by then you are back to full on your energy and have lost valuable resources in not using your offensive strikes. Rather, the better use of Premeditation is to amp up Slice and Dice before a fight. Slice and Dice does not break stealth. Therefore, it is very useful to use right before opening.
7. Improved Gouge/Glyph of Gouge: Gouge is a sub rogue's most powerful weapon, and it's a shame no rogues use it. It deals 1500 damage, costs 30 energy glyphed, and incapacitates for 6 seconds every 10 seconds. It's the perfect amount of time to exit combat and restealth in a 1v1 scenario, and offers plenty of control in a 2v2 scenario. The only problem is that it gets broken easily by Rupture, which is another reason why Rupture should not be used for maximizing damage.
8. DW Specialization: Sub rogues have some of the most potent autoattack damage in the game, due to their Slice N Dice constantly being up during combat(on a side note, getting Improved Slice N Dice in any shape or form is generally a good move too). Therefore, DW Specialization is a good place to put points in for extra damage.
Hope this helped some people.