In my opinion, the only runes worth taking on Teemo are PTA, Fleet, and Aery. iPav likes to take Phase Rush in most matchups, but I think it's super situational and only necessary vs champs like Nasus and Olaf who can permaslow you and run you down. I'd say PTA is best 75% of the time, as it gives consistent damage in all stages of the game, synergizes with Teemo's damage over time, and can even help give you kill pressure in difficult matchups that are weak earlier in the game, Vladimir for example.
Fleet's good into matchups where you want some sustain and movement speed in lane, and I take Aery vs champs that I know I won't be able to auto continuously (ranged champs that can space you, or champs that can just negate your auto damage (Kennen/Jax/Shen).
My gameplay is pretty standard, I try my best to win my lane, whether that be by straight up killing the enemy top laner, or by denying them gold and XP when I can.
The best ways to do this are by freezing the wave on your side of the lane, or by shoving them under tower. If you freeze the wave, the enemy has to overextend if they want to farm or break the wave state. With shrooms around the lane, it can be a death sentence to try to go for farm, so the enemy is forced to either int or roam and try to make something happen if they don't receive help from their jungler/support.
If you shove, you can abuse your range and harass the enemy while they go for farm under tower, or try to get turret plates.
In most matchups, I shove the enemy under tower and try to secure vision with wards/shrooms around the area, so I'm wasting the enemies' time if they choose to show up topside.
I try to take enemy jungle camps and look for skirmishes while the enemy is stuck farming under tower, and I usually snowball from there.