You are correct, using just the toothpaste was fairly a satisfactory result, but you can try what I did, buff your headlights using wet sandpaper soaked in soapy water, 1000 Grit or 2000 Grit sandpaper would do depending upon the condition of your lights, and when you're done, dry the headlights and start applying Brass Polish, you can buy that from any hardware store, costs around Rs.130, I applied several layers of it using a cotton fabric and got great results
And I'll take some night pictures right away, will upload them in a while 
Applying plastic polish once a week isn't really necessary after you've done this DIY, just apply some plastic UV protectant and you're good to go
