Before you learn to cope with your allergies, you need to know what is causing them. You can go to the doctor and have them poke you with needles and figure out what you are allergic to. This can range from cats to flowers to even some dust in the corner of your room. Also, one thing to remember, is that during the summer months, if you do not have central air, you will most likely need an air conditioner, which will make your allergies worse during the night when you are asleep and breathing the air in. The best thing to do instead would be to put a fan in your window during the night and deal with not having cold air blasting into the room.
Also, I take a claritin D or sudafed right before going to bed or else I end up waking up at night not being able to breath or having my nose so runny I need to get tissues.
I also keep sinus headache pills stocked up during the summer because the more allergens you take in, the higher your risk of not only getting sinus infections, but also sinus headaches.
Oh and btw, if you thought about using one of those netty pots to clean out your sinuses, make sure you read up on them. I have heard of water being trapped in the sinuses and causing really bad sinus problems.