I personally like to take flash and ignite because early game people will try to gank you or rush a Teemo to keep him under control. To avoid this I poke as often as I can (this will Come over time) The early ignite stacked on with Your Toxic Shot and Blinding Dart gives you the ability to counter most champions. If you are Laning against a Jax you have to play more safe at the beginning because a fed Jax will hunt you down every time. If you would like to be more proactive for your team I would recommend using Teleport instead of ignite so that you can gank bottom (If warded)

The early dorans ring is very important because what I have found is that when you end up with the dorans ring it allows you to harass with your blinding dart, also the healing potions will allow you to sustain and not die to quickly early. With the totem what I would always recommend is placing the ward a little late around 2:45 in the river bush that way you can see a late gank. WARNING this does leave you for a level 2 gank form jungle play safe and farm. I personally think the Narshors tooth is the best item on Teemo because it gives a good amount of AP early and attack speed making it easy to harass and farm. The hurricane will allow you the ability to put heavy pressure on towers due to wave clear. The Deathcap is the best AP item in the game because of the passive this will allow you to be effective with little amount of ability power. The Mask will allow your mushrooms to do the max amount of damage because the enemy will have a movement speed impairment. The void staff to top it off will allow you to nuke down 3 enemies at once also allowing your team to provide a lot of pressure. If you are going against a fiddle sticks or some one with a lot of CC I highly recommend QSS.

I rush my Narshor's tooth and hurricane for simple farm.... Once you get these items you will be able to get the rest of your build fairly quick... This allows you to push tower's like crazy. Since season 4 I have found that with the limited warding that does go on during lower ELO it is extremely important to place your shroom's in the right place.

Shrooming is probably your most important role.... For top lane once you hit level 6 your first shroom should go into the river bush to slow down ganks (Jungles hate shrooms and it will lower how much they actually try to gank you) if you are owning your lane continue to just push your lane this will cause the enemy team to come and find you and one of the best parts about teemo is his passive. Once you notice you are pulling attention hide in place's like middle of lane or off to the right of the lane (most people will look for a teemo that activated his passive in bush's some times its better to hide in plain site) Once they have determined that you "went back to town" you appear and continue pushing. This allows you to have an Enemy Search party for teemo (normally all 5 of them) so you kite around there jungle allowing your team to push and you to laugh ur *** off when they pass you. IF YOU ARE IN DANGER everyone is after you they know where you are..... (this sucks) if you are invisible I let go of my mouse and keyboard and wait for them to leave or your team to respond. If you know the enemy team has oracles just go ahead target the squishy one's and take the death. But all in all while pushing your lane shroom all Entrance's from the jungle.

Pros:
-Mobility
-Can be used as more of a distraction than actually carrying the team
-Blind dart shuts down a lot of champs
-Stealth
-Can split push very well
-Scales well with AP and attack speed
-SHROOOMS
-Tank killer

-Cons
-If you get behind you will not be able to do much without help
-Easy to gank if you burn your speed boost
-Little life
-Jax
-Not really well in team fights
-You will nee your team to work together because normally you would want a tanky top