How do i find what's the best way to prevent allergies?

A very open question: but in short, we don't know unless we get exposed, if we know that we are allergic to something, food, medicine or pollen for instance, avoidance is the best strategy then, if we can't, then certain medicines for whatever disease is caused by the exposure, such asthma or rhinosinusitis, is the way to prevent complications, certain patients would benefit from desensitization, good luck