Hello, this is Theta159 here giving you my first guide. This is really how I personally like to play Teemo, and I don't expect everyone to like it. However, I like to mix Teemo with an attack damage and an ability power aspect. Remember as with all builds, they are just a general guideline and must be changed based on thousands of different situations. That is something every league player has to learn themselves. And eventually create their own builds for each champion they play. I will give a couple situations where I change up the build, like if there is a strong enemy AB presence.

NOTE IT IS IMPROBABLE THAT YOU WILL BE ABLE TO COMPLETE THIS ENTIRE BUILD BY THE END OF THE GAME. IF YOU FOLLOW IT STRAIGHT THROUGH THE BUILD WORKS!

There are many different kinds of runes you can choose. I personally like to focus on attack speed and ability power runes. Using health runes as well since Teemo has a low amount of health. Again this all is based on your own playing style. Since you will never know what champions you will be facing, you can not set them up for a specific fight. Be broad when you are choosing your runes. And I really suggest following the Attack speed, ability power, and health runes.

Teemo's poison is very helpful for farming. When you fire at minions hit each with two shots then move to the next. The poison will kill the minion the rest of the way. This makes for more efficient farming. However, if you are competing for minion kills, you may want to finish the minions of to ensure you get the gold for the kill. Always remember the importance of last hitting. Another great way of farming is lining your ultimate down the middle of a lane. Make sure the mushrooms are spread a decent distance apart. This will allow you to kill minions with out even being there.

As I said before there are thousands of situations that can change the item build you use. Here I would like to describe some of those situations. For instance:

If the enemy team has a strong ability power presence, you will want to gain magic resistance immediately after getting boots. I personally like to go for lich bane starting with null magic mantle. If you gain an early advantage with this little magic resistance, you can keep them down enough where you will not need a lot of magic resistance later. If not, more magic resistance will be needed and those items will be taken away from your attack and ability power.

If health is rapidly becoming a problem, for what ever reason, instead of using rabadons deathcap, use one or two rylai's crystal scepters. This will quickly give teemo any needed health.

If the enemy team has more attack damage, the solution is similar to ability power. After you buy your boots, focus on armor. Then continue with your build.

If your team has a strong ability power presence, consider making your build more of an attack damage build. The enemy team will then have to have armor and magic resist. Taking up item slots that could be used for more important items.

These are some of the more common issues I face when playing Teemo. But I can not express enough that there are thousands of different situations that could occur. As a League player, you will have to crafting your own builds to each situation and interpreting the outcome.

Pros:
~His passive ability "stealth" is excellent for ambushes.
~His poison is great for taking down enemies that are running away.
~His ultimate can be used not only as traps for slowing, and killing enemies, it is great for farming and using them as wards.
~His DPS can be insane.
~His high speeds

Cons:
~He has very low health at the start of the game
~He can be ganked easily if mushrooms are not around him. He has no kiting ability.
~He will me targeted first many of times.

So if you actually read this far, I must have done something right. At this point I just want to tell you that I use Teemo as one of my main champions. Besides for him, I like to stick with other ability power, ranged champions. In the future, I may post more builds. I would also like to hear your criticisms, as this is my first build I posted and would like to improve. However I don't care to hear how I am totally wrong about everything, and what a waste this post is. Thank you for reading and good luck.