It depends on the cause and severity. If I had a headache I would take some sort of over the counter medication such as Tylenol or Ibuprofen. Drinking fluids is always helpful. Going for a swim can be relaxing. Maybe take a nap. Just chillax, and maybe watch a movie.
It has been scientifically proven that headaches are not caused by a deficiency of painkillers. You might get temporary relief (at the cost of beating up your kidneys) but the headaches will return again and again. YES - water and a sleep is good advice. So is massaging Essential Oil of Lavender into your temples. But to clear your headaches so that they don't keep coming back, you need to talk to a local Homeopath. They will check out al the factors that are causing your headaches and give you a custom-fitted remedy and a life-style protocol that steers you away from triggers that bring on headaches.