When playing at solo top you really need map vision so you need to buy some wards to make sure you don't get ganked. Teemo is a really squishy target that is easy to gank.

When laning try to be carefull of getting harrased else they can just 1 combo you. You need to farm really good cuz if you lane against tanks like Cho'gath or Shen you will have some trouble whit getting kills.

Try not to seek for Teamfights, you will prob. be focused and you are a very squishy target so be carefull for teamfights.
If it happends that you come in a teamfight you should try being in the back of you team so you both can do dmg and not being attacked.