I've always just had a personal preference of more bottom end and less of that real hissy/fizzy high end. I'm really not incredibly versed on mixing and mastering, so I don't know a plethora of terms or methods of correction, so I really don't know how else I can offer advice -- and I'm certainly not one to just throw out ideas if I didn't trust that they'd work haha.
However, a lot of what I'm not exactly 100% fond of in this song of yours boils down to my own personal preference and is not necessarily what would be "best" or "ideal" by any means.