Telling signs of someone who is "new" or "unskilled" at a champion
Tries to use ult as an escape
Q's 3 times in a row without AA'ing in between
Tries to use his Ult>W waaaay too often instead of putting down a turret
15 Comments
ulting in a teamfight or duel
I disagree with the Fiddle claim, depending on the situation it might be the correct call, and it does take experience to know and be willing to sacrifice ultimate for escaping purposes.
Another similar situation would be Shen or Sion running away to safety through their ulti, since it's always better to waste CD than giving enemies extra leads.
By far the biggest one I see? Honestly? Doesn't even have to do with a champion.
It's when someone uses 
on a minion/ward about three feet from their turret.
If you don't know what I'm talking about, you may be one of those people and have just never fully read the spell's description. Which I guess a lot of people just didn't, because I still see this all the time, even over a year after I started, with people who have more games in overall than I do.
But people using 
who don't W friendly minions qualify. Or 
newcomers who use his ult's second cast as an engage on a full-health target with no one else nearby. Ooh, or 
using Zhonya's after he triggers his ult. not realizing it's not the same as Morgana's. I see that a lot, too.
Towers dives because dont worry guys i have egg
R>R>R
Ahri, why do you keep headbutting yourself into that wall?
"Why do I have Bork and PD? For my passive of course!"
Not using 
. "I don't need it. I have an escape/initiation."
Headbutts.
Stacks the barrels all in one place.
Literally a slot machine with Pick-a-card.
Heals herself to death at lvl 1.
Jumps into every fight regardless.
Playing
Has to use ult to run away and they aren't in the enemy base.
Bubbles when she walks forward without seeing a skill fire.
just stands there attacking and not paying attention to health, dies, and does not by anything other than a vision ward... his excuse is "I wanted to see what a vision ward does" riot... please do something about this, I do not have the time to teach someone the basics of the game during a match, and I don't mean punish them for going in a match they're not ready for. That's just as unnecessary as getting banned from the game for a bot match DC.
: Puts the plant down, then uses an ability on it instead of getting the surprise plant turret.
: Facechecks a bush. EVER. [Hint: her seeds are wards]
: Gets Q first.
: Does not know you can hit the button again to make the tornado go. [yes I was guilty of this myself]