Doing a Neti pot or a sinus cleanse squeeze bottle like Tattvamasi has daily, when your sinuses are NOT stuffed up to where you can't breathe out of them, is a good practice. Keep in mind that if you do this kind of practice when your sinuses are clogged, it can aggravate the situation moreso!
Also, dissolving salt into the warm, purified water is a must. It takes a little practice, but you can find that "sweet spot" with the amount of salt in your nasal wash. Too little & it'll sting like you inhaled fresh water. Too much & it'll sting differently, like you inhaled sea water. Just the right amount & it feels just like your own bodily fluids that are supposed to be in your body, i.e. no sting.
The strategy here is to do nasal washes long enough (3 months, 6 months, a year, two years, etc.) to where you've loosened & expectorated all the mucoidal plaque that has fastened itself in your sinuses. Believe me, you've got lots of plaque up there! Anyone who uses mucus-suppressing drugs does. It's the norm in our symptom-suppressing culture. Rather than excrete & expectorate the stuff that needs to come out, we prefer the convenience of suppressing all of it only to have that bite us in the ass later on in life (but that is an entirely different thread altogether!)
Keep in mind also that when employing sinus rinsing practices that you MUST bend over forwards or to the side while you're doing it so that the saline solution can get up into your upper sinuses. This is best acheived in the shower or bath or over a big sink. It is not a pretty sight.
It is not a practice that "proper", Western civilization would ever condone, but it's crucial to healthy respiratory health just like any other hygenic practice, i.e. brushing your teeth, wiping your ass & washing your hands.
All that having been said, there are more herbal options out there also. There are a few good quality anti-histamine/anti-inflammatory combinations on the market that can really help a lot. These will usually have a combo of Quercetin (a flavanoid found in leaves, barks &/or seeds of certain food plants), Bromelain (a proteolytic enzyme from pineappple stem), Turmeric (a yellow/orange fragrant spice from Asia), Pantothenic Acid (Vitamin B-5), & Ascorbic Acid (Vitamin C).
There are also some very effective Chinese medicines for acute symptoms like runny nose, watery eyes, etc. The most popular one is called "Bi Yan Pian" (pronounced Bee Yawn Pee-yawn) which basically translates as "stuck nose energy tablet" to put it in layman's terms. Keep in mind that any of the Chinese nasal formulas for acute symptoms that contain the herb "Cang Er Zi" (pronounced "Song Er Tsih" ) or Xanthium sibiricum should be taken daily for not more than 3 months. This herb is highly effective at opening up the sinuses & dissolving phlegm, but has a mild liver toxicity that renders it's long-term use unsuggestable. There are sinus formulas without this herb that are more appropriate for long-term use if needed.
Finally, keep in mind that all allergies ultimately stem from emotional reactions, typically the feelings of "this is not right" or "that is not good" (directed at any phenomenon). Theses blockages/reactions begin when we are very small children, even though often times the physical symptoms do not manifest until many decades later. Practices such as tai chi, yoga & meditation can help reduce the over-all affects of latent, emotional reactions & thus our physical allergic reactions over time. A good acupuncturist is a god-send in these cases also as acupuncture is, at it's most fundamental, anti-allergy engendering.
Hope this helps in some way. Peace.
Freedom's so hard
When we are all bound by laws
Etched in the scheme of nature's own hand
Unseen by all those who fail
In their pursuit of fate