Improvement help?

Does anybody have tips on how to improve? I've been trying to get into this game since 2010 or 2011 but I keep leaving because of how frustrating the game is. The toxicity puts me off. I get called a troll or get insulted by team mates, everyone judges you and calls you names because you're bad at the game. The game difficulty puts me off too. It's hard to improve at all when people are so toxic in every match. I play the game for about a week before I leave for a year or two and then come back for another week. The cycle repeats itself. I'm trying not to leave the game again because I really want to improve at it. It's incredibly hard when the community is so toxic. Whenever I'm in a fight I loose track of my champ, I don't know where my mouse is or my camera flies to the other side of the map. I can't keep track of anything that's going on around me and I don't even know who's attacking me. I keep feeding the team without actually wanting to. When did you guys ever improve? I'm starting to loose hope and I just start to think I'll never improve. I feel like I'm missing out on the game when I keep leaving.