You just gotta stick to it, the rocket league progress curve is incredibly steep at the beginning, but if you just brute force through it for a bit you'll reach the first plateau where you actually manage to touch the ball once in a while. Getting over that plateau is a different story and the progress curve is much slower after that.

Also go and do the training sets, start with the easiest ones until you nail them then move on to the next one, etc.

RL is pretty much the only game I still play regularly because I've been playing it for a long time and I can just do one game if I don't have much time, most other games require too much of my very limited free time.