How can I improve my basketball skills over the summerr.?

Im on my schools b-ball team and I want to get better over the summer. But I don't know how! My coach said some players practice all summer but never improve, so I need some big help b/c Ive only been playing bball for a year. I need help with the fundamentals, like ball-handling, box-out, and its crucial that I become better at dribbling. Especially w/ my left hand. So plz leave any comments, tips, youtube videos, personal notes, ANYTHING is helpful at this point ! Nd, Im serious about this, so please only serious comments ! Thank youu.