The most common cause of headaches is dehydration. My experience with this type of headache is extensive; for me, it manifests as a pain behind my eyes, drawing the pain toward the middle of my forehead (may not make sense to anyone else, but can't think how else to describe it); there's also, often, nausea involved, which makes it difficult to take medication for it. I've learned to drink enough water to keep it from happening most of the time, but if I do get dehydrated and headachy, here's my solution: a nice cup of HERBAL tea. Peppermint, ginger or marshmallow (it's an herb, not the candy) teas are soothing to the stomach; hot water is also soothing as is a small amount of sugar. I sip that down and usually, by the time I'm done with that first cup of tea, my stomach has settled and I can get down to the business of chugging water. The marshmallow tea is my favorite, by the way; I add a couple drops of vanilla extract and use a lump/tsp of flavored sugar (I flavor my sugar with cinnamon, cloves and other spices) so it tastes and feels good; great for the stomach flu too. Anywhoo...
If you're dealing with migraines, avoiding triggers can help: MSG (monosodium glutamate) is a big trigger for me, and can be found in canned soups (pretty much all of Campbell's low sodium soups have it), sometimes as a flavoring in chips, cheap Chinese/Asian food, etc. Other triggers include smells--I have to be very careful with what kind of candle or air freshener that I use. I can't be around Scensty, but Party Light candles/melts are fine. Recently, my stress levels have been through the roof (thanks to work), so I've had to go to the doctor and get some imitrex, which does help. I've also discovered that keeping up on my vitamin C reduces my chances of getting migraines.
If you are able to take the time, try laying down with either a hot or cold washcloth over your eyes--both can feel wonderful and can help with relaxing the facial muscles, with the added benefit of blocking out more light. Lightly massaging the scalp with your fingertips can really help too. Hope you get some relief!