If you know you have a sinus infection, then rest and antibiotics are probably the most surefire methods. But other things can cause sinusitis, including allergic reactions and gastroesophageal reflux. Do you have a fever, nausea or vomiting? If it's bad enough, go in to see a doctor, especially if it's not getting better.
Get a humidifier or vaporizor. Keep it nearby as much as possible and especially sleep with it on. Works wonders. Just make sure to keep it clean so bacteria don't grow in it.
I grew up not having many headaches. But within the last year and a half I have been getting headaches off & on...just never went to a Dr for them till this week. I was told at the clinic that quite a few people here get headaches from allergies/stuff in the air.