teemo is a champ with a lot of different builds that can be used. hes also one of the few champs who can stealth and afterwards you'll have a boost of attack speed for a while
(btw this is my first build guide)

1.you deal at least 177.87(normal)+42(wit's end)+20(malady)=239.87+4% of the target's maximum Health(Madred's Bloodrazor) also the attack slows
2.your attack speed is crazy high
3.with ignite and exhaust a kill is a guarantee
4.build pisses alot of people because of the amount of kills

for marks the attack speed helps early game but you can also use armor pen marks
for seals i went ad because of the lack of ad from my items but you can use mana seals as well
for glyphs i used health for staying in lane longer but you can use ap per level as well
for quintessence i used aromr pen but you can also go magic resist per level for laning longer

i set up the masteries for an agressive yet safe laning way but you can go any way you want to.

my build is a quick dps build but if you want to make it better you could use Black cleaver instead of nashors tooth.

With your runes and dorans blade you should be able to harass along with blinding dart until you can go back and get the Berserker's Greaves which guarantees a kill if you still haven't got one yet.By now you can get kills easily and if not just keep harassing.

by now you should have malady and recurve bow so u can start getting killing sprees and double kills and you should also get the lizard buff so you can gank. If all goes well you should have all your items except for nashors tooth and maldreds bloodrazor so you can get kills quickly and with move quick escape right after.

now that you have finished your build you can kill even a cho'gath with feastx6 and warmog armor also at max stack. An avreage score is 19/4/9

pros
1.blinding dart helps alot when you're trying to kill a melee champ like tryn
2.Blinding Dart resets the attack timer when used, which allows 2 rapid-fire attacks. This is extremely important to learn how to use throughout the game. Opening with a normal attack, immediately using Blinding Dart, then proceeding to autoattack will apply great burst damage, even during laning. Try mastering this combo to use it on the fly and you'll increase your AP/AS damage tremendously.
3.Noxious Trap is a good sub for wards
cons
1.gettting stuned is your worst nightmare
2.When fighting against a Twisted Fate, be careful because if he uses Destiny everything on the map will be revealed including Noxious Traps.
3.if a minion follows you and u pass a mushroom that mushroom will be wasted.

ad/as:only quick attacking(7.5/10)
ap:too mana consuming(7/10)
hybrid:it's okay but it doesn't go well with toxic shot98.5/10)
my build: works well with all of the skills for teemo (10/10)