Thanks!
I have a few more things to mention. First thing, everyone has a champion they play the best with. It's the champion the best fits their style of play. If you like to be in the midst of battle, you may want to pick a "tanky" character, someone like Alistar, Nunu, or Leona. Maybe you like picking up kills from afar, so your champion might be Ashe, Caitlyn, or Xerath. If you like to drop huge amounts of damage onto a player, then Annie is your champ. If you want to be sneaky, then you should grab Shaco, Twitch or Evelynn. Discover your playstyle, then pick your champ accordingly. While good players can do well with numerous champions, each player has that one that "fits like a glove".
Second thing, after you pick your champion, look up different build guides to know which items you should buy. It's more than just following a guide, however. Learn what each item does to improve the champ and why you'd want it. Learn other items too, sometimes you need to grab certain items due to the circumstances of that game.
Finally, Youtube videos can really help. By watching experienced players, you can pick up some serious tips and tricks that'll help you win games. For example, Alistar, Tristana, Singed, and Volibear all have abilities that "throw/push" other champions in a specific direction. If you're playing as one of these champions, you can use this ability to pick up some neat kills by
flinging enemy champions into your turrets. Or, you can use the same ability to save a teammate (or yourself) to disrupt a chase.
