NEW CHANGE, BOOTS START. Skip D ring and 2 pots, get items you don't need to sell. Play safe early and with early boots you can run down and follow up ganks better or roam quicker to help your Jungle.
Playing with this Dark Harvest build do not push early so you are not gankable. Do not poke to much and let the wave push towards your tower. With the added attack speed you will be able to start a freeze and start damaging the enemy. Then as it pushes back to his tower, they should be so low, they can't all in you without dying. In certain matchups, you will need to play super safe early (Example Irellia). With the increased attack speed in unfavorable lane matchups, you can push out and attempt to get rift when the jungle is ganking botside.
I find that building any defensive items early will only hurt your team fighting damage later and is not worth it.

OUT DATED VIDS- Will post 10.9 vids soon.

I am not great at video content, but wanted to provide something so here it is.

https://youtu.be/s5sNU_u_90M

https://www.youtube.com/watch?v=YXNQbYBwp9w

https://www.youtube.com/watch?v=VXgo3NjD5aY

https://www.youtube.com/watch?v=ei6UQaXun1g&t=1217s

Darius - one mistake and he can kill you, or several Teammates

8.23 Teemo VS JAX https://www.youtube.com/watch?v=-80yDoZvSvE&feature=youtu.be
8.21 Teemo VS Sion https://youtu.be/mexwOwZSn9U
8.18 Videos: Teemo VS Urgot -- https://www.youtube.com/watch?
Teemo VS RIVEN https://www.youtube.com/watch?v=nXIyNstt42I&t=7s

v=uRq8YgO98jA&feature=youtu.be
8.17: PENTA!!!! https://www.youtube.com/watch?v=7I4g0tM0oWc
Teemo VS Fiora: https://youtu.be/bHsbQ8VXvq0
A good example of why I take Barrier. This is a match against a Tryndamere.
https://youtu.be/5b9vwc7hcJc

8.16 NEW VIDEO:
Video using Grasp against Malphite: https://youtu.be/Lb2tnl3ysQA
How to win after a 0-5 START https://youtu.be/r8pnxFrlUlI

HOW TO START IN LANE...Shove first 2 waves, then ward, then freeze.
https://www.youtube.com/watch?v=qqdwv1BmVPo

Uncut- Shows the power of Executors Calling, and the importance of matching the rotation.
https://www.youtube.com/watch?v=0nTQuPHQQYM

Recent Video of the build poping off. Teemo Carry!!! It shows how it scales into late game.
www.youtube.com/watch?v=wvakr9SAwNU

LEARN TO WALL FLASH! Here are 2 escapes in one game.
https://www.youtube.com/watch?v=2iTA8rK-L2M

BEEMO VS MAGE- A good example how to beat AP.
https://youtu.be/Pq-9W4dvWAk

How to Carry when you ADC AFK farms.
https://youtu.be/udUEIXhdAl8

This is a big change from the first item Gunblade, it trades off lifesteal for added attack speed and lane pressure. The added attack speed will improve your CS'ing- and will make you CS better than your average with other Teemo builds. I didn't post Grasp runes because it only allows you to post one page of runes. I will list it in another section.

11/15/2018--- On my other account TrickyMAC (NA) I am at Plat 1 with this build and is going really well. I should be able to hit Diamond with it when I get some time to play more. This build will also get complaints by your team and will blame every loss because you build AD- It's always Teemo's fault. JK- Stay strong, Teemo can be played many was. GOOD LUCK! Hit me up any time for questions.
The build just worked at Plat 5 level. I didn't need to make any changes, I am now ranked Plat 4 using this build.
UPDATE PLAT 3!!!! WHOHOOO!
UPDATE PLAT 2! now with this build. I'm super pumped this is working as I get higher in ELO. Changing out Nashors for Rageblade seems to be a good fit also.
UPDATE PLAT 1!!!! For some reason the games are getting easier. Everyone is making smart plays. Entered Placements with 56% win rate.
MADE IT TO DIAMOND!!! --As soon after I got Diamond, I feel like I changed the way I play (not for the better), and need to focus on what works, and not be as defensive.
UPDATE D5- Just made it into placements for the first time of D4. I'm getting used to this elo. The build is actually still working, however quick matches make it hard for my build to scale. I am overall still very pleased with this build.
UPDATE DIAMOND 4!: So 3rd time was a charm in placements. How high can this build tame me? 55% win rate.
UPDATE: Adjusting to the Nerf of D-ring, I De-Ranked back to D5. I am going to be testing and tweaking the build to make it more well rounded. Entertaining the idea of using Aery again.
Back to Diamond 5: Learning this new patch meta. So far attempts at scuttle put me in way to much danger so I'm thinking about ignoring it for now, and maybe only try to get it, when its super free.
6/26/18 UPDATE: Playing less rank because Diamond with the new patches are making games way to short, and it not allowing my build to scale. I'm making a smurf to test things, and will jump into ranked on that and see how high I can go. I still think this is a good from bronze-high Plat.
UPDATE: I have been working using Beserks and BORK on my new Smurf account TRICKYMAC. I am raking up on it and will do a full post when I feel I am maxing out the rank level.

UPDATE 8/20/2018: I have been playing on a smurf account to figure out, and refine my on hit build. It allows me to test more things and see what works. This is the account and the build has been working super good. I am currently at Plat 3 on it with a 74% win rate in the last 20 games, and as i figured stuff out above 60% win rate. I expect to keep climbing and will update more. I will also update the narrative for this build to, to explain it's strengths and weaknesses.http://na.op.gg/summoner/userName=Trickymac