Patty,
When I was in high school we always had games right after school, like at 3pm. I would usually always work out after the games and never before. This kept me strong and I was never tight before games. Once I got into college, we would work out in the mornings as we do now in pro ball and, as Racab said, we always did it under supervision.
As you go along playing ball, you will realize that it really is impossible to make gains in strength during the season, so your goal should always be to MAINTAIN your strength throughout.