I've worked on car brakes all my life, so here's a few questions / tips.

Are these the original pads? If so, 68K is probably about time to replace at least the front ones. If you already replaced them, use only good quality semi-metallic or carbon-metallic pads (nor organic - they generally squeak). How do your rotors look? They should be smooth and shiny with no grooves or channels cut into them. Make sure your calipers slide freely on their pins. Have you flushed the brake fluid (should be done at least every 2 years)?