A healthy immune system can help with sinuses if it is triggered by bacteria, viruses, or fungus/mold...
Here's an article on boosting immunity: http://www.nutriliving.com/blog/boost-your-immune-system-naturally
A good immune-boosting ingredient is reishi mushroom...(good if fungus is not the cause of your condition)
In addition, Basil, garlic, parsley, horeseradish, wasabi mustard, peppermint, and rosemary extract have been shown to work as a natural expectorant to clear out any mucus.
Also... ginger works well with clearing sinuses and organic cold-preessed virgin coconut oil is a good antimicrobial.
A few other suggestions are:
-Use a vaporizer or humidifier
-Create a steam bath by taking a hot shower, or filling your sink with hot water, then placing a towel over your head as you lean over the sink
-Breathe in the steam from a hot cup of tea
- drink hot liquids
- try a Neti pot for nasal irrigation
- avoid sugary foods and try foods rich in anti-inflammatory omega-3 fatty acids
- choose anti-inflammatory foods: http://www.nutriliving.com/blog/top-10-anti-inflammatory-foods
Let us know what works for you!