Attempting to become better
I am a newer player, so I don't have a whole lot of experience, but I still feel that at this point I should be better at the game than I am. I play Sivir a lot, since she has range and damage, but unfortunately I tend to rush into places where I shouldn't be and then feed the other team. On the flip side sometimes I am just way to cautious and end up leaving my teammates to die when I could have gotten a kill or at least kept my teammate alive. I have thought that perhaps I am just not a very good ADC, but I've been told to refrain from purchasing other champs because I should save for runes when the time comes. I have payed Vi and Garen as well as a few others when they come onto the free rotation but otherwise I only really play Sivir. I'm a bit afraid of trying to learn another champion since I am finally starting to grasp all of Sivir's abilities and the way you use them. Farming is also an issue although I feel as though I have become a bit better. I tend to have bad map awareness as well. I'll either focus on minions and forget to look around or miss last hitting since I am too busy looking to see where my opponent is.
I would really appreciate some tips or tricks or just general advice.
Thanks in advance.