Drink lots of fluids. Fluids can help dilute secretions and promote drainage.
Eat plenty of fresh fruits and vegetables for vitamin C. Eat foods rich in vitamin E too because it has anti-inflammatory benefits. Eat foods rich in zinc because it boosts the immune system and may have anti-inflammatory benefits too.
Quit smoking. Smoking causes nasal and sinus inflammation. Heat and dry air can produce swollen, dry nasal membranes that are predisposed to sinusitis. Use a humidifier. Some foods are natural decongestants. These include garlic, onions, chillies, herbs, spices, ginger, thyme, cloves and cinnamon