How to become a better football player over the off season?

I am playing football this year as a freshman at my high school. I am very tall for my age but very lean but strong, only have average speed, and play defensive end. Football is defenately my main sport and i want to become as good as posible over the off season. Should i lift all off season until next summer, lift in the winter and spring but also play rugby, of lift in the winter and do track in the spring which i am leaning to doing? Also if i do track what events should i do?