First off, the first thing you must do is gain this type of mind set where you are constantly asking yourself
"What must I do to win?" When you do that, you got look at your mini map, analyze the situation, press tab, analyze the situation, and than make a game plan immediately, and you must be able to do this within five to ten seconds. That might sound unreasonable but once you gain a tactical mind, it's very possible and easy to accomplish. To win as fluently as possible you must be able to make quick and decisive game plans based off the situation the game is in. Constantly ask yourself "what must I do to win?" the "I" is very important, for your not going "what does my team need to do?" your going "what do I need to do?" Be it.
-instantly kill Adc in team fights
-Focus hard on the top side of the map
-Focus on protect your teamates
-Go to this side of the map and get this tower right now
Constantly and once again be asking the "what must I do?", plan accordingly and quickly.
Secondly but also just as important, remain calm at all times, don't flame, don't get pissy, remain calm. The moment you lose your cool is when you start making stupid decisions and throw the game.
Realize how important your life is. So you say you don't die often, but think of the time you do die, every time you are dead, is a moment you are no longer on the map and give the opponents a break with you not on it. Try not to die, so you can be constantly creating pressure on the enemy team. When you do die, make it worth it.
Thirdly Learn a multitude of stratagies so you aren't a one strat pony
-Learn the art of split pushing
-Learn the art of roaming
-Learn the art of lane dominance
These are just some of the strategies for you to learn, learn them at a basic level so you can switch stratagies when one plan is no longer working. Far to often I see lower level players stick to the same plan over and over again even though it is clearly not working. If you failed to do something 3 times in a row, than clearly your plan is not working and it needs to be changed.
I'll end this here, but if you are a mid main you should main 4 types of champions
1-An Ap mage 
2-An Ad mid laner 
3-A supportive mid laner 
4-Your trust nobody, always win main 
A: In many team comps, your teams will be idiots and chose horrible team comps with ALL ad champs and no cc, this is why you will need to learn a mage, so you can provide ap damage while also providing crowd control.
B: While this situation will be very rare, once in a while you will have a team with far to much magic damage, so knowing a champion to play in AD will be helpful in these scenarios
C: Sometimes you will have lots of carries on your team, much like with situation A you need cc, but sometimes you don't need cc, sometimes all you need is a second support on your team to be played in mid to buff those carries. This can be a very powerful strat
D: A champion you can get 10 kills on easy per game, a champion where you stomp on everyone, a champion where you feel completely confident on.
Once you complete this list and have 1 champion for each of those situations you will notice your life becoming easier
