Hello.
With Teemo you can begin your match with a dorans ring and a couple hp potions.Nashors Tooth or Sorcerer's shoes depends on the magic resistance your opponent have if it is more than 30-45 you should take Sorcerer's shoes(Ss) if it isn't more than 30 and still not much damage with Q buy Ss.After you have bought your Ss Nashor's Tooth is a pretty good item for more abillity power and attack speed.When your build have DoransRing Nashor'sToothSorcerer'sShoes,you will have two more items to complete the core that items will be Liandries Torment and Rabadon's Deathcap.Buy Haunting Guise first then complete Rabadon's Deathcap and after you have Rabadon's complete Liandrie's Torment.The last two items are situational.If you want to trap buy Lich Bane and take Blue Buff and place mushrooms everywhere at the jungle and some wards at blindspots(communicate with sup)If you pull your enemies at bushes there will be no escape also Void Staff is pretty effective on this situation BUT you have only 1 chance to beat your enemies at the jungle(with your team of course).After that you will just team fight somewhere else you pick the place not them.Trolling with Teemo and placing mushrooms at the jungle got me a PENTAKILL(The first).