Hi.
My friends call me Liam.
I started playing league in the middle of season 9. Yeah, I'm still new to this game and learning.
The first champion I got was Ahri (I'm a fan of naruto so obviously the nine tail cute girl was my choice). I bought Nocturne 1 week after. I saw his Ultimate skill. It instantly killed the enemy in the preview so I thought "WOOOW THAT'S AWWWSOME". Well, it didn't killed my enemies instantly :\ I wasn't disappointed though. I liked and like him a lot as my first favorite champion in League. He was my favorite for a long long time until I met this beautiful Angel named, "Kayle". I played a few games and really like her. I went to read everything about her, read and saved all her quotes and I really like her personality. It's the main reason I like her. Not because she's a lategame hypercarry or because of her unique style (but of course that's an important and lovely thing about her. She evolves."I will grow stronger"). I like herself.

• She's a beautiful angel.
• She's a Lategame Hypercarry who can also Support other Carries.
• Really good at teamfights because of her AOE damage and R.
• Even if you play bad early, you'll be useful for your team because of your Supportive skills and your powerspike.
• Great Split Pusher.
• Can slow enemies, Provide MS boost and heal, her E is a finisher dependent on enemy's missing health and her R gives Invulnerability.
• Can build both AD and AP.
• ...

• Weak early game.
• Weak against CC.
• Has many unfavorable matchups and can get punished so hard early game.
• Requires Patience, something that lots of people don't have.
  ...

Precision

My main pick is Press the because it's the best rune for your early/mid game and also the best for teamfights or when your jungler ganks your lane. You can use it to poke melee enemies and it's better against squishy enemies. However, I pick over it when Enemy team is Tanky or I'm going for On-Hit builds. Other runes here doesn't really worth much. Remember that Surviving the early game is important but it doesn't matter if you don't won't have a lategame at all. And ofc, I don't suggest as it's not stable. I don't like random things...

I pick because I usually don't have any Item that provides mana (usually, Only Leach Bane) and I spam W a lot for bonus MS and heal. You can pick if you want but being sure that you'll have mana for fights is more important to me. With it I can farm faster and get lots of healing/MS boost to run escape, help, chase.

is the best option here. You can pick against HeavyCC teams.

Well, Your E is a perfect finisher and this rune works well with it. And as a late game kayle, It's easy to bring your opponents to low health xD. However, Kayle can work well with all of these. You can pick Because it works well with your R. And you can pick Against Tanky teams.

Choose the last one dependent on your enemy's attack type.

considered the changes in patch 10.18, you can now go for max E and focus on farming/poking with your E.

You need to focus on farming and getting Exp. Play as safe as possible especially before lvl6. Remember that it's always okay if you're behind in CS and don't kill yourself because of some minions. It doesn't mean you shouldn't farm, but the priority is staying alive and getting the exp and farm safely before lvl6. When you get ranged attacks farming will be easier (especially if your lane opponent is melee). Also, don't really look for fair trades because you'll most likely lose most of them early. Try to freeze the minion wave ahead of your tower and if your opponent still puts you under pressure, farm under the cover.
tips:
1_ You can use your Q to farm early (doesn't mean you should use it for a single caster minion :|)
2_ You can use your E to kill the canon minion (especially before lvl6.)
3_ Your W is more of a escape tool early game. Don't spam it for health unless you're gonna recall soon and just wanna make sure you'll stay alive a little longer.
4_ Keep your E to finish the enemy. Or use it when your enemy has a low health and it can actually deal some early damage.
5_ Use your W on your jungler when he/she ganks you so you'll get Bonus MS. You can also give him/her your R to make sure he won't die and you'll get the kill.
6_ Play and but Items Dependent on your enemies. You shouldn't always follow a certain path. There are different ways to reach the Light :)

1_ Don't pick Kayle for any adc. Pick when you're with someone you can trust early. Most likely a duo or ADCs like Vayne, Kai'Sa, etc.
2_ Don't spam your skills early. You better not be much aggressive before lvl6.

First of all, you shouldn't really be here.
But if you are, remember that your weak. Play safe, focus on farming and providing River vision. Don't gank unless you're sure you'll be okay. It's the best if you try to be safe especially before lvl6 and focus on farming and leveling up (and Vision, if you can't gank your teammates you should at least help them not to get ganked by enemy jg hard). Also remember that the enemy jg might decide to hide inside your jg and kill you. So choose the path that it's less likely for him/her to appear on. (Starting on Top side is usually a good way).
And one last thing, go for On-Hit build and have patience.

Have patience and focus.