Initially medical professionals suggest using a nasal spray with saline solution every 12 hours. Although to be honest, that never worked for me. I always need a decongestant. If your congestion is high up in the sinus cavities, you might want to try a decongestant nasal spray but not to use it continuously. Just use it to get clear. If you don't want to use something invasive, you can go topical by putting a spot of Vicks Vapo Rub, just a dab on the tip of your nose or just above your lip. Breathing it in opens you up within 30 minutes.
Doctors say the best solution is to use a Neti pot - several times per day, until it is gone, and then at least twice a week thereafter to keep nasal passages clear of toxins and debris.