Once your reach level 20, you embark on a quest to acquire the Poisoning skill. Poisons can only be put on melee weapons and are self-only. You cannot share poisons. Poisoning can drastically increase your damage potential. They also do not stack; they overwrite each other. If you crash, you lose the poison effect on your weapons. If you change zones (you see the loading screen, such as instances) you lose the poison effect as well.
Poison Quests
Alliance
You can do this easily at level 20.
Head to Stormwind and visit Mathias Shaw in the rogue headquarters. He’ll send you to see Agent Kearnen in Westfall. Problem is, he’s stealth and a pain to find if you don’t know where to look. Head to Westfall and go to the lower right corner, until you reach a tower like structure. It’s just south of the road to Duskwood. Against a tree near the riverbank, you’ll find Kearnen. Talking to him starts the next step. Outside the tower you’ll find a Malformed Drone. Go into Stealth and Pick Pocket him for the Defias Tower Key. If you mess up, kill him and he’ll spawn again in a minute or so. Once you have the key, head into the tower in Stealth mode, avoiding the guards. At the top is Klaven himself, a 26 Elite. Head behind him and Sap him. Use your Lock Pick ability on the chest next to him and collect the book. You need a fair amount of skill to open it, but if you spent anytime in Redridge you should be at 80 skill and that’ll be fine. Return to Mathias to get the Poisoning skill.
Horde
You can do the first 2 parts alone at 20, the last part you will need some friends.
Head to Ogrimmar and talk to Shenthul in the Cleft of Shadow. Once you talk to him, target him again and type “/salute” (minus the quotations) to move onto the next step. He’ll send you out to the Barrens to meet Taskmaster Fizzule. Get to the Barrens and head north to the Sludge Fen. Find Fizzule and target him. Get close enough and fire the Flare Gun twice and then type “/salute” (minus the quotations). He’ll acknowledge you and start you on the next part. Head over to the tower and start killing the Venture Co. creatures the quest lists. Find

Gallwix and get some friends to help you kill him, as he’s a 26 elite. Then find Silixiz and Pick Pocket him for the tower key. The chances of him detecting you are very high so have a group ready to help you out. Enter the tower and kill everything on the way up until you reach the chest. At the top is another 25 elite. Kill it and open the chest to collect the Cache. Return to Shenthul in Ogrimmar to get your poison skill.

Poison Listing
Numbers in () are ranks of a given poison.

Poison Details
Anesthetic PoisonAnesthetic PoisonAnesthetic PoisonAnesthetic PoisonAnesthetic Poison – Very similar to Instant Poison, but generates no additional threat. If I used Instant Poison in groups, this would be a great alternative. Sure, less potential damage but you save energy not having to use Feint as much. However, since I use Deadly/Crippling Poison in groups, this poison doesn’t have a whole lot of use.
Blinding PowderBlinding PowderBlinding PowderBlinding PowderBlinding PowderBlinding Powder – See the Blind skill above. Has limited uses but excels in PvP.
Crippling PoisonCrippling PoisonCrippling PoisonCrippling PoisonCrippling PoisonCrippling PoisonCrippling Poison – Use this in instances. Targets seem to love to run around when low on life and if your Kidney Shot misses, this will help tremendously. You can also use it in PvP to slow people from running away. This poison is listed at 30% chance of hitting but it feels more like 99% chance. When you have it on, you’ll nearly always see it affecting your target. Point of fact, you shouldn’t use any poison but this one in PvP on the main hand and Mind Numbing on the other.
Deadly PoisonDeadly PoisonDeadly PoisonDeadly PoisonDeadly Poison – If you don’t use stuns, then this is a great poison. You don’t really use it in groups however since you’ll be killing so fast the poisons don’t have time to go into effect. It has some uses solo but again; you want the creature dead before it really has a chance to come into effect. Instant Poison would be a better choice; especially when you consider this can easily break stuns. It has very limited uses such as long boss encounters.
Mind Numbing PoisonMind Numbing PoisonMind Numbing PoisonMind Numbing PoisonMind Numbing PoisonMind Numbing Poison – I have yet to find a really solid use for this poison in PvE. Solo, I don’t let casters get their spells to work in the first place. The same goes for when I’m in a group. Perhaps there’d be a use for the higher end instance caster types where Kick/Gouge/Kidney Shot have trouble landing and you’re fighting them non-stop. All in all though, it’s not that useful. It does however make fear a 9 second cast, a spell that I loathe. In PvP, this should be on your off-hand weapon most of the time. It really plays havock with casters.
Wound PoisonWound PoisonWound PoisonWound Poison – Stacks to decrease the heals they can receive. The only use you’ll ever find for this is with elite creatures that can heal and you can’t stop them. 5 stacks of the highest level is 50% less healing they are receiving per cast/tick. Another use is on the Emperor in Blackrock Depths when you don’t want to kill the princess. Using this

will prevent the princess from healing the Emperor continuously. This is pretty much useless in all other cases that I’ve experienced.