Halogen headlights lose up to 50% of their brightness with age. Just putting in new ones should brighten things up. Brighter halogens have shorter life span. I plan on replacing my low beams every fall before Daylight Savings Time ends for best winter nighttime visibility, and my high beams every two years.

To my knowledge, Phillips currently offers the brightest DOT-legal halogen bulbs. Here's my current setup, even brighter low beam, and even brighter high beam.

Depending on your state's inspection laws on lighting, you could try aftermarket LED bulbs, but since they aren't tested and DOT approved for on-road use, they can be really hit-or-miss in brightness, longevity, and (in the high beams) ability to actually aim light down the road. Low beam projector lenses can be more forgiving of non-halogen replacement bulbs, but the reflector housing of the high beams is fine-tuned only for halogen.