Stretch. It is very important in the world of dance, the more you stretch, the more you will improve your flexibility. You will stretch every day in class, but you may want to add stretching when you wake up or before you go to sleep to improve flexibility, but make sure you are warm enough so you don't hurt yourself.
If you have the space, you may want to put a barre somewhere in your home, preferably in a room with wood floors. Even if you do not have the perfect flooring, you will be able to stretch more if you have one.