need to get better

i dont know whats up, i played this game forever, i was plat season 1, i was gold season 2 and 3, i quit for a few years and came back and have been silver 5 for months, and i never even know what kiting was, so many things ive learned but im still a bad player, i rarely win anymore. why am i not getting any better, i been playing for about 3 months now and i still just lose