My son was an infant when he had his first seizure. It was the same day he had vaccination shots. The next year or so after that, if he had an overly exhausting day or if he had a the quick onset of a fever (fever spike), he would have some small type of seizure. We never administered any medications other than Tylenol and/or Ibuprofen in order to keep fevers at bay. As long as we minimized the potential for fevers and over-exhaustion, he was fine.
He is now 7 y/o and he has not had any type of seizure in about 2 years (knock on wood).
My daughter also had febrile seizures very early on. She never had full blown seizures like the 3 or 4 that my son had, but they were nerve racking to deal with as a parent, nonetheless. She is now 5 y/o and she has not had any type of reaction to fever or over-exhaustion in almost a year (knock on wood).
The "small seizures" that both of my children had seem to always happen at night. My theory is that the over-exhaustion they had from too much play or from the beginnings of a cold were from their bodies' reaction to some small spike in their temperature. If they started to get a fever, we could prevent the spike with Tylenol or Ibuprofen and no adverse reactions would occur. If we did not catch it or didn't slow the fever spike soon enough, they would have a reaction.
The seizures were always more difficult for us as parents than for our children. Many times they would wet themselves during their small seizure and, right away, their body would relax and they would go straight to sleep only to wake up the next morning with no recollection of what happened. By having them go pee before bed seemed to be another preventative measure (maybe a full bladder is added stress to their little bodies).
My daughter still has two more shots she is required to have before starting Kindergarten, so I hope that we are able to keep these shots from bringing on any seizures. I hope some of this information may help.