I too struggle with seasonal allergies.  In the water I use the same equalization techniques.
Out of the water I just make just I am taking my antihistamines and decongestants.  Seasonal allergies can change day by day;  so when I'm preparing to dive I take it whether I need it or not (during my allergy season). 
Also alcohol makes allergy affects worse, so when preparing to dive, no alcohol the day before.