What should I consider if there has been only a single seizure?

Seizure. With only a single seizure you would need a workup by a neurologist to rule out any underlying problems, and in most cases if eeg is normal then one would just follow you for further issues.
Normal life. General rule is that many people will experience only a single seizure in their life. There is often a cause such as toxicity, infection, drug use, injury, etc. If you take good care of your health, recurrent seizures may never occur.