Crummy headlights - Can't see, need upgrade

If the headlight lenses are cloudy, cleaning and polishing them so that they are again transparent will make a noticeable difference. (They will often then require touching up from time to time since the polishing process also tends to remove much of the UV protective layer of the plastic. Arguably a better alternative is to replace the lens assembly entirely.)

For those with light bars, please don't use them on the highway; they almost inevitably cause a lot of glare in other driver's eyes, and very often have rather poor pattern control otherwise for good visibility. Many illuminate the roadway near by directly in front of the vehicle far too brightly in comparison with farther away, which is unhelpful--it draws your eyes to that area, too close to be able to react to anything you see at highway speeds, and due to the increased ambient light makes the pupils close down more and thus reduces one's ability to see things farther away in the distance. Furthermore, they are not DOT approved for highway use. For off-road use where speeds are much lower, they are often very good.