First some background: In League of Legends i'm currently a gold rated player on the NA server - I have been playing since before season 1, and I want to help improve the player base as a whole. Now, I understand you may be thinking "this guy is only gold, he sucks, I'm gonna go watch theoddones stream" and for some of you, you may be right to do so. However, As a gold rated player, I am not here to give advice to the plat players, the diamond or challenger players, or even really the gold players (though a different perspective can be helpful). I'm simply writing this to help the bottom 90% of the community - the bronze and silver players.
I thoroughly believe one of the most important things to develop in League of Legends is your mindset. We have all played with players who rage at every mistake their teammate makes, yell "luck" at all their deaths, and blame their teammates for their own mistakes. These players suck. They are a pain to deal with and make the game miserably un-fun for everyone on both teams. However, as players we lean towards that direction - we do not like to acknowledge our mistakes, and want to believe some form of black magic or the people around us is to blame.
Usually though, its our own fault. If we admit it, that is our first step towards improving. If you watch voyboy or the oddones stream, you will constantly see them calling out their own mistakes, analyzing what they should have done to have a better outcome, and learning from their mistakes. If you are looking towards improving, one of the most important things you can do is be your own harshest critic. You died? what could you have done to live? Kill 3 of your enemies? How could you have stopped the other two from getting away? For your sanity however, be realistic though. If you pull off a beautiful play, bask in it. Every time you die though, use that time to figure out how they killed you and what you could have done.
Lastly, treat your allies AND your enemies as if they were your mothers friends. Don't swear at them, don't criticize their play, and don't harass them. Trash talk is for small people who don't have enough self confidence to trust their own abilities - besides, this is a game. Not everyone takes it as seriously as you, and everyone ultimately plays to have fun. If you want people to do their most to win, don't demoralize them. Your teammates will play better for a player who is nice to them and doesn't constantly criticize them.
Ultimately, League of Legends is a game for 99.9% of us. We will never make any money from it, and it will rob of our precious, precious youth. Thus, the goal is to have fun. It doesn't matter if you are in a normal game, a ranked game or a *ugh* dominion game, ignore anything in your mind that tells you that the only important thing is winning, and learn from the game. If you do, you will begin to win more, have calmer, stress free games, and you will see your elo rise.
Next time we learn about the importance of warding and good ward spots. read