Don't use over the counter nasal decongestants (i.e. Afrin) for more than 3 consecutive days. This can cause "rebound congestion" and keep the cycle going.
Also try using your Neti pot every day, OTC Zyrtec or Claritin (store brand is fine), Zatidor if you have eye allergies, and Benedryl or Sudafed when needed, like when you feel you're getting a sinus headache.
Keep your bed linens clean, and use your A/C keeping your windows up in both your car and home to keep the pollen out.