Live in the gym, mix it up with everyone you can any chance you get.
Experience is the best, and the only real teacher.
If you were smart, you would remember that.
There's an old saying.
Amateur boxing is a glorified sparring match.
Amateur boxing is not like professional boxing. It is not even judged the same.
My advice, PUNCH OUTPUT! Throw more punches and don't look out of control and you will win in amateurs.
If you are a southpaw, the straight left and right hook are excellent counters.
Look up yuriorkis Gamboa
There's so much that can happen in a sparring match. Your best bet to learn is to start sparring, and you'll naturally learn everything.
Like what style to use and what are good counters to use as a southpaw