Becoming Better at MathBecoming Better at Math was closed on the grounds of being primarily opinion-based. It is community wiki with soft-question and advice tags. Though there are many possible answers (hence the CW), I do not find the question to be opinion based, as it is a call for guidance from experienced mathematics students, who in general do not disagree about most fundamental aspects of learning mathematics. (In other words, though opinion-based answers to this questions may exist, certainly not all answers are opinion-based.) This question could serve as a useful collection of practical advice specifically aimed at high school aged students preparing to major in math in college.