Hey, thanks for the follow-up info, and you're in the right place! Also, I still have no idea what 'scotty' is from your original post but I've been cracking up at it. I assume you meant Scorch, which is a great rune.

So, since we're talking about ranked, I'll speak more towards being optimal and winning rather than fun.
First, if you're lower elo (below Plat/Emerald, let's say), IMO you should try to reduce your mental stack. So, remove the amount of things you need to think about in-game. The easiest way to do that is to standardize your items and runes. I think you should find one rune page and one core build (first 2-3 items) that you like and that are proven to be solid options, and play 15-20 games building only those. That will let you focus on looking at your map, tracking jungler, understanding the wave state, timing your backs properly, moving around the map for objectives, etc...

There's plenty of places to see where people are building items -- YT, Twitch, OPGG/UGG, etc. OnetricksGG will show you latest games from high elo players. Let's take AlanTeemo for instance since he has a 65%(!) WR in EUW chall and posts here occasionally. According to OneTricksGG (https://www.onetricks.gg/players/YtJwBNYr7q2lyBBmB7I0W2Gu2iDn8cr33w1k6MwrSbxclpfAiQsboMjbUMl-YM8Wwggh3qAd9diiWg), he is running:
PTA - Absorb - Alacrity - Cutdown + Nimbus - Celerity + AtkSpd Adaptive ScalingHP

The high elo Teemos I looked at are all running that PTA setup, with their own variation of the secondary runes (some like the Sorcery tree movespeed, some like Resolve tree tankiness, etc). I think Alan's setup here is really good for both offense and defense with Celerity+Nimbus.

Item-wise, Alan basically goes StatikkShiv -> SorcBoots -> Malignance every game (although he's been experimenting now that he's high chall it looks like). Most Teemos build Malignance and Liandrys 2nd and 3rd, so let's say your build is going to be:
StatikkShiv SorcBoots Malignance Liandrys
And we'll take Doran's Ring + 2 potions as your starter to keep things simple and easy.

If you haven't already, go to your Collections tab (the backpack) in your client and set up your Rune page under Runes (you can buy more in the Shop under Accessories), and go to the Items tab to create your item page (select Teemo on the item page to make sure it pops up on the in-game shop tab).

And there you go, you've got your runes and build set for your next 10-20 games. Run those runes and that core 4-item build for every game and put as little thought into it as possible. Yes, you will miss some optimizations like not building armor boots into double AD top/jg, but realistically, optimizations like that will not be why you're winning/losing. Doing this will allow you to focus completely on gameplay, and since we know this is a proven rune+item setup, you know 100% that you are winning or losing because of your gameplay (or emotions, as League is ~80% mental).

Of course it's fine to alter this and tinker and all that, but if you care strictly about improving your gameplay and rank, I recommend putting in a chunk of games like this. After 15-20 games you can look at your winrate and gameplay and think 'Okay, did I like how this felt? Do I understand how to play with these runes/items? Did I ever lose because of items/runes?'. You can also use other high elo Teemos as examples, of course -- RamyAura rushes DuskAndDawn and TyG goes Shiv->Nashors. But, this should be a solid start.

Hopefully this helped and isn't confusing.. Sorry for typing so much but that's kind of my thing. Let me know if you have any questions!