Practice on your own at home, in your neighborhood with friends, or even at school if you have the chance! Juggling, wall-ball (knocking your ball against a wall and work on receiving it. Make sure there are no windows!!!), dribbling--all of these are perfect activities to work on during your free time to make yourself a better player.
Check out the twelve videos in The Coaching Manual's playlist below for some great examples of skills to practice at home: