Just make sure to get plenty of sleep, for starters.That'll help immensely.
Other than that, the only things you have to worry about are more homework and the freaky stuff puberty does to your brain which'll make little things seem big. At the very least I suggest you engage in some extracurricular activities and with friends but still allowing time for homework, to keep your sanity in check. You want to keep yourself from getting overwhelmed or careless (which can make you more overwhelmed later), and allocating your time while still finding time to enjoy life is a nice habit to carry over into your work life.
