Teemo is my favorite champion for two reasons. He has his own amazing wards, and he really annoys your opponent. So if you suck at buying wards and love making your opponents angry, hes the pick for you. He is a good counter pick to non-mobile melee champions.

Some people take deathfire or ferocity but i prefer the Thunderlord's decree. It hits harder faster. The deathfire is good too because it makes your mushrooms deal more damage. Also if you suck at last hitting, I would recommend savagery over wanderer.

The attack speed marks make the early game much easier. Last hitting isn't too tuff on him. Armor is almost always a must, early game damage prevention seems good. Scaling MR is also great. They prevent damage and the longer the game the more damage they prevent.

So the overall most important item on teemo is the Frozen Hammer. It slows your opponent's down so you can kite super easy. It also improves your tankyness! With how squishy teemo is, any extra tankyness feels super good. The attack speed items improve your CSing and also help kiting. Wits End and Zhonya's both make you tankyer and also add damage.

Skills seem pretty self explanatory. You want to get your poison early because it is your main damage output, and the level three movement speed because pre-level 6 ganks hurt.

Teleport is also a good option. I prefer ignite because the extra damage is amazing and if they have people with lifesteal or spellvamp you will not regret it. If you pick teleport don't forget you can tele to your own mushrooms.

This is very important. Early game you should use them to block the jungler from ganking you. The river is a great spot and the tri bush top lane. I like to put ones to and from the tri bush on all side too. Killing your opponents control wards is very useful. makes them spend more money to kill your mushrooms. If you are trying to kill large number of minions you can drop a mushroom in the middle of them. All highly traveled areas are good to drop mushrooms in too. examples are your opponents jungle, dragon, river (where scuttle doesn't walk). Near middles bush. By your opponents razor talons jungle minions. Krugs tower bush and by the opening near krugs. Also Mushrooms near your opponents blue and red buffs help. The double as wards so keeping them by baron and dragon is smart too.

Pros
+Annoying for opponents
+Easy farmer
+Free wards
+High damage output
+Blind

Cons
-Has a universal taunt just by being teemo
-Squishy to the max
-lacks a good escape other than move quick, easy to jump on
-Did I mention Squish!

In team fights blind adc, kill squishys after adc.