Here is a thing that worked for me.
Herbal Pills
It has absolutely no side effects as it is herbal. It not only stops you from having sinuses but increases your immune system. Many times sinuses are caused by extreme heat in the body. Like when you wake up, do you feel your body is burning? Or for example, when you wake up, take a moist cold towel and put it on your lower back. If you feel cold burning your skin, it is probably your body is generating excessive heat.
That heat can be from many things, may be indigestion, stress, or improper liver functions.
Another thing to try is go to acupuncture. See if you have a medical school of alternative medicine close to your area. Usually they charge you like $15 per visit, and that includes about 60 minutes of therapy. The trick here is how good the doctor is to find the exact cause of the sinuses, so that he can use those pressure points to release your sinuses.
Pontiac_C_S's method is not bad either in. In Yoga it is called Half Shoulderstand -- Ardha Sarvangasana
Promotes proper thyroid function, strengthens abdomen, stretches upper back, improves blood circulation, induces relaxation
You probably remember doing this as a kid. Lie on your back and lift your legs up into air. Place your hands on your lower back for support, resting your elbows and lower arms on the ground. Make sure your weight is on your shoulders and mid to upper back -- not your neck. Breathe deeply and hold for at the posture for at least 5-10 breaths, increasing the hold over time. To come down, slowly lower your legs, keeping them very straight -- a little workout for your abdominal muscles.