1. Have a stable internet connection.
2.Know your comfortable role: Don't say "I can play all of that" anyone can play any role but of course there is one role that you are the best
3. Watch tutorial videos on youtube about laning phase, lane control, warding etc.
4. Try the "one trick method" which you will play only with champ and be good with it.
5. Try not to be tilted because of teammates by: using the mute button, or turning off the option allchat/teamchat in interface settings. ( it might be hard to communicate with this but its effective atleast for me)
6. Have a positive mindset/mental, if you die once it's okay don't be negative.
7. Grind until you get good at the game, there is no other way.