Be sure you sit next to the smart kid. Be sure that you do ALL of the problems on ALL of your homework assignments. You cannot just do most of the problems on all of the assignments or do all of the problems on most of the assignments.
Every problem is important.
By not doing some of the problems you leave gaps in your mathematical knowledge, gaps that will allow other mathematical concepts to fall through. Pay attention at ALL times in class. Again, paying attention most of the time is not nearly good enough. Think of it like reading a book. You can't comprehend a book if you skip every fourth word or if you decide not to read random chapters.