League of legends tips

I played lol since season 3 and i've seen many people playing the game with 1000+ hours playing like they never touched the game before.
What are the best tips you can give others that feels like nobody knows it?

I'll start: before you start the baron, set a ward behind the wall to see if the enemy is waiting for his chance.
I know, that's pretty basic, but it seems like most people just don't get it.