A good grade will be a natural consequence of understanding the subject. Rather than thinking about the grade as such you should worry about understanding the subject. It's more efficient!
Another point about grades: students sometimes seem to think that there is a well defined and unique way to assign a grade to a given piece of work, and sometimes the instructor misses it and just needs to be informed of that failure. Actually, assigning grades is mostly arbitrary within a wide range, and determined by the grader's judgment of what is reasonable. Once that judgment is made the only thing that matters is consistency, because we must be fair. That's the major reason why instructors are hesitant to change grades, particularly in large classes.
Fine print, your comments, more links, Peter Alfeld, PA1UM