The simple/easy and cheap thing I did was drop in some brighter halogens. You trade off service life for brightness I suppose, but mine are 3 years old now and still going fine. The headlights went from notably "how the Hell are these sucky stock headlights DOT legal dim" to "functional". When I drive at night now, I am not blown away by how bright my lights are, but not struggling to see either. The simply work acceptably like they should have from the factory.
There is a whole host of other more involved/expensive options too of course. These are the bulbs I am using to good effect:
There is a whole host of other more involved/expensive options too of course. These are the bulbs I am using to good effect: