There are several homemade ways that are safe to you but detrimental to your headlights.If they are glass, toothpaste will work just fine but finding something at home to SAFELY clean transparent plastic is the $1000000 question. Don't make the mistake of using toothpaste on plastic headlight lens, It will cloud them up permanently.I'm assuming you already know not to use any kind of sandpaper.
When it comes to headlights, you have to think about the replacement cost if you mess them up.Some will cost over a thousand dollars.Beware these so called headlight cleaning "KITS". These abrasive sandpaper based cleaning methods will cause more harm to the surface of your headlight than good.When you damage your headlight with abrasives, there is no turning back.There is no safe homemade cleaner but there is a safe professional one that does not rely on damaging abrasives as 99% of most headlight cleaning Kits do.Most headlights don't need sanding, they need deoxidizing.Pure liquid and non abrasive system is the only way to go with today's expensive acrylic headlight lens.