Advice you’d give to a complete beginner

For complete beginners:

Choose either AD (attack damage), AP (ability power), or tank, and focus on mostly playing/learning those champs and items for awhile, there is a lot to take in so narrowing some things down early on will help a lot.

Hold tab while dead to read enemy items so you can start to learn other items as well as learn what other champs do most typically (AD/AP/Tank etc)

Runes are selected pre-game (you might have pre-set rune pages still, have to gain some account levels to unlock custom pages). Basically they give more damage or tankiness for the most part under various conditions. Im pretty sure they are going to give recommended or most common rune choices for champs in champ select soon so people don't have to use 3rd party apps to quickly change them anymore, so that will be good for you.

Spam ARAM (all random all mid game mode) and/or intermediate bot games to learn new champs. They are low stress, faster, and you can take your time to read the abilities. It's better to go vs bots in a game that ends in 20 minutes or less and you can for sure get fed and see how the champ feels when it's strong rather than maybe taking multiple games that could end up going long and you are behind and struggling the entire time.

Auto-attack resets.. Look it up, learn it, practice it. A lot of champs use them, and they are mostly pretty simple but very important.

Mobile damage-dealers champ recommends:

Top: Jax, Irelia, Wukong, Camille
Jg: Ekko, Hecarim, Kayn, Vi and Master Yi is perfectly fine as well ESPECIALLY for someone new
Mid: Ekko, Talon, Zed, Diana, Vex
ADC: Tristana, Lucian, Samira
Sup: Pyke

Not all of these champs are exactly noob friendly but they can all be highly mobile with dashes or speed ups or ability resets to keep chasing/fighting/killing. You can look up difficulty tier list to get a general idea.

/r/summonerschool Thread