It is actually a bad idea to make decisions based upon making yourself look better for scholarships. Seek actions that are intrinsically beneficial for your personal, intellectual and professional development. However . . . you should know that such an approach happens to correlate closely with what scholarship judges value in candidates. You become a strong scholarship candidate by striving towards meaningful ends. Pursue excellence in challenging classes.
Good grades are mostly prerequisite for scholarship success.
But scholarship winners seek more than the grade. Train yourself to thirst for knowledge. Work on your communication skills, verbal and written, whenever the opportunity presents itself. Few doors open without them . . . Expand your knowledge of the world.