Offseason training

I have just finished my first triathlon season, where I competed in two races. I've fallen in love with the sport and want to continue. Next season, I really want to improve so I want to keep in shape and improve my skills during the offseason. Does anyone have any suggestions as to what kind of training approach I should take in the offseason? How often should I train and how intense? What kinds of things can I do to prepare my body for hardcore training once tri season approcahes? Any suggestions would be greatly appreciated.