Track and Field Summer Training?

I'm going to be a Junior in high school and I want to be prepared for the year's Track and Field seasons. I'm mainly focusing on the indoor track season right now, since it's the sport I do right after Soccer. I'm a high jumper, I run the 55m hurdles, and I run the 4x400m. I'd like to know what I should do in order to get better and be prepared for the season. All help is appreciated!