Getting into medical school is a competitive process.
But good grades alone is not all that counts. You should try to get the best grades you can possibly get. On top of that, try to get involved in volunteer work that relates to the health care field. When you get closer to college, investigate the track record of the college regarding getting their students into medical school. Look for other leadership opportunities (again, volunteer work is always considered an asset).
Hope this helps, and good luck!