Yeah, yeah, yeah, everyone could use this, but reducing the stress in your life can have a positive impact on your body's reaction to allergens, including seasonal ones. Getting more exercise, meditating, and even doing something as simple as practicing deep breathing when you feel frazzled can greatly impact your stress levels, which, in turn, can help keep your allergies at bay (or at least keep them from taking over your whole life).
Get better air filters
Swapping out conventional air filters in your home for HEPA filters can significantly reduce the number of allergens floating around in your air trying to ruin your quality of life. Studies show that adding HEPA filters to work on your whole house are more effective than ones that only work in one zone of your home, and it's a pretty quick, simple fix (though you'll have to bust open your wallet to do it).
Check your home for mold
Mold is gross. It's also bad for your health, and can wreak havoc on your allergies, particularly during warmer months. Inside the home, mold can spring up from water condensation, even in areas you never think about, such as the corner in your bedroom that's hidden by your dresser. Exhaust fans in the bathroom, dehumidifiers (especially on lower levels), running your central air conditioner earlier in the season, and fixing any leaks promptly will help prevent mold from taking hold in your home in the first place. HEPA filters can also trap mold spores, but cleaning mold with a damp cloth and a cleaning agent as soon as you find it is your best bet (for large-scale mold problems, you might want to consult a professional).