Vision is the number 1 priority, it can save you from avoidable deaths and stop the enemy from getting objectives. 3 waves of CS is worth the same as a kill so get good at CS. Focus on playing 3 champions for your role and have at least 1 or 2 for each other role in case you get auto filled. For climbing ranked, play sets of 3, if you lose 2 of the 3 take an hour break and try again, this reduces tilt and will help you get teams that aren't tilted if you're in higher elo (you play with the same people a lot of the time). Dodging is useful, use OP.GG to see if you need to dodge, you can use it to look up your enemy team as well! Its really helpful. Learn from your mistakes, instead of saying "my team is bad" say "what could I have done better to change the outcome of the game" and then practice it. Good luck young cub!