Looking for some tips on how to play better and have a better overall performance in the game

Hey i have been playing League of Legends since about the start of season 4. After getting into bronze 3 from my series i have climbed up to silver 1 and 2 but i am stuck there and seem to not been climbing at all anymore. Maybe I'm just not good enough to carry anymore, maybe ive just hit the leave i'm supposed to be at. I don't want sound like someone crying over a bad team or a feeding lane. I understand that if i don't win it's my fault and i am hoping someone could shed some light on my situation. I also have a tendency to go on tilt while in game, if i make a bad missplay or mistake i feel bad about it and don't play as well ater. Thankyou for taking the time to read this and have a nice day.